Ryan Stark | Blackstone Laboratories

About Ryan Stark

Ryan started at Blackstone in 1997 after graduating from Purdue University with a degree in mechanical engineering. Ryan is responsible for writing and maintaining Blackstone's software program, setting up and managing the lab, writing reports, and a million other things that need to be done in a business. When he's not kicking ass in the lab or writing code, Ryan enjoys putting his pilot's license to good use, working on his '84 Chevy 3/4 ton, and raising his kids. As an experiment, Ryan ran Aeroshell W65 — an oil with no zinc or phosphorus in it — in his Chevy to determine if the hype over ZDDP (zinc dithiophosphate) is all that or not, figuring if the experiment ruined his engine, well, he's rebuilt it before. (Spoiler alert: The engine was fine. To read about the endeavor and see pictures from the rebuild, read the article "Rebuilding a GM 350 Engine.")

Emergency!

Unless you rent just one plane a lot, you never really know about a rental plane. You would like to think that it sees careful maintenance all the time, and I’m sure most of them do, but as long as some other person is flying it, it could have problems lurking that don’t show up every flight. Like most pilots, I would like to own a plane someday — something I could fly a lot and get familiar with. Unfortunately, a Republic SeaBee isn’t in the cards right now, so I’ll be renting for the time being. That leaves the possibility for unknown problems lurking that have to be dealt with on the fly (so to speak).

Half power

For me, my first experience with a problem in a rental was actually during flight training. I was flying a Cessna 152 out of Fort Wayne International. I was just going up solo for some touch and go’s and on my first climb-out the engine went to about half power. Thankfully it stayed at half power and I was able to fly the pattern and land without incident.

When I got back in to the flight training building and told my instructor what happened, I got a sense that she didn’t believe me. And sure enough, when we both took it up, everything was fine. She mentioned something like, “I’ll bet there was water in the tanks” (I thought, No, I sumped the tanks and they were clean — I do work in a lab, dammit!) and that’s the last I heard about it. Of course, I was renting the plane, so I don’t know if it had happened before or after my incident, or if something was fixed afterwards that may have been the cause.

In any case, I didn’t panic and made a nice landing (the plane was reusable) so really didn’t think much about it until several years later.

When suddenly…

I have had my private pilot’s license for a few years now, and I have been renting a 172N with the Continental O-300. I got checked out in it just fine and had taken a few flights previously by myself. On this particular day, I went up with my Dad (Jim Stark, Blackstone’s founder) and his wife on a sightseeing trip.

We flew north for about 30 minutes looking at the lakes of northeast Indiana, and we had just finished a turn south to head back when the engine started shaking. No little shudder either, but the kind of shaking a dog would make trying to pass razorblades — at least what I would imagine a dog would look like. My dog was never so dumb as to eat razorblades to start with.

Anyway, the engine started shaking really bad. My father (also a pilot) initially said “Get the carb heat on!” and I thought, of course! Carb heat! Continentals are prone to carb ice and I have had nightmares of having to force land an aircraft for just that reason. I’m not sure if I would have thought of that myself, so I was sure glad to have him sitting in the right seat.

I pulled on the carb heat so hard I thought the knob might come off. We sat expectantly for a minute, both waiting for the engine to smooth out. Unfortunately, that didn’t happen. We still had power, but the shaking was bad enough that the thought of a 30-minute flight back to Fort Wayne wasn’t appealing, so I looked at Dad and said, “We’re going back to Angola to land!”

Angola is a town about as close to the northeast corner of Indiana that you can get. It has a beautiful airport with a paved 5,000-foot east-west runway. We were only about five minutes away, but as you can imagine, it seemed to take about an hour to get there.

The carb heat was on the whole time yet the engine never smoothed out, so I figured the engine had some serious issues. The landing was uneventful and as we pulled up to the ramp the engine was still shaking, so we decided to do a mag check.

The right mag check produced no change, but the engine almost died on the left mag. We tested this several times to make sure it was correct and then shut the engine down. One of the best things about the Angola airport is they have an airport car that’s available for situations just like this. It was a late ’90s Ford Explorer that shook almost as bad as the airplane, but hey, beggars can’t be choosers.

I called the FBO where I rented the plane, told them the situation, and then drove home. After an hour’s drive, I pulled into the FBO, gave them the keys and paid my bill. Yes, full price for the time I had the airplane. No discounts for having to make an emergency landing and no allowance for my stepmother needing new underwear. It was okay though, I was just happy to be alive and back in Fort Wayne.

The bright side

Now, the good thing about renting an airplane is, when it breaks, all you have to do is say “Your plane is messed up” and leave. I don’t worry about having to schedule/pay the mechanic, call the people who were renting it afterwards and tell them to make other plans, no hangar fees, no insurance, no fixing knobs that got pulled off.

The bad part about it is that you really never get to know the aircraft and engine ¾ what’s normal operation and what’s not. After a few days, I get a call from the FBO manager who said the engine had a stuck valve. I was fairly amazed because I suspected the horrible mag check denoted something electrical as the problem.

We happened to be doing the oil analysis on this engine, so I checked that to see what it looked like. Aside from a little excess copper, it looked pretty good. However, the O-300 does have bronze exhaust valve guides, so this should have been a warning, at least to be on the lookout for valve problems.

Signs of the problem

Since this incident, I have learned that a really bad mag check is a common symptom of a stuck valve. Some other common symptoms are below.

Morning sickness — When an engine starts rough first time consistently, not just in the morning, without plug fouling
Temporary roughness on climb out or in cruise — this happens when a valve momentarily sticks, then shakes loose
Intermittent rough idle that’s not caused by carb ice (this needs to be ruled out)

If I had been the sole operator of this aircraft, I might have identified some of the other symptoms and put two and two together. Instead, I was not aware of any issues at all. In all fairness, maybe there weren’t any, I don’t know. But I know these symptoms now and I’ll be sure to look for them in the future.

By Ryan Stark|2024-09-18T14:17:40-04:00July 18, 2023|Aircraft, Articles|Comments Off

Building an Engine Dehumidifier

Continental and Lycoming typically rate their engine life from 1,600 to 2,000 hours of operation between overhauls on most models. However, the only owners likely to achieve that kind of rated performance are those who use their aircraft on a nearly daily basis. Why? The reason is not the flying. It’s the parking!

A primary culprit for premature aircraft engine overhaul is corrosion caused by condensation that occurs after shutdown. Aircraft engines that are used daily frequently reach their rated TBO because liquid condensate is boiled off on a regular basis. Low use rate often results in reduced engine life.

Air Inlet Fitting In Oil Filler Cap

As the engine cools and the internal temperature drops below the dew point, liquid moisture condenses out of the vapor and clings to internal engine surfaces. This liquid water then resumes its ongoing process of eating up your engine from the inside out. However, if the dew point can be made sufficiently low, then liquid water will never form. This engine dehumidifier provides a continuous positive pressure injection of extremely dry air (dew point approximately -100^oF) on a 24/7 continuous flow basis. It is recovered at the crankcase blow-by vent, returned to the pump, dried again and re-injected in the oil fill port of the engine.

How it works

The dehumidifier is connected the engine as soon after engine shutdown as possible, before the engine cools. It is then run on a 24/7 basis. A small aquarium-type air pump forces ambient humid air though plastic bottle containing silica gel (this is the stuff used in shipping and storing aircraft engines and electronics).

Air Fitting For Oil Cap

The silica gel has a great affinity for moisture and literally sucks it out of the air. The dried air is filtered and injected into the engine crankcase. Any moisture inside the engine vaporizes with the incoming dry air and is moved by the constant positive pressure from the air pump to the crankcase blow-by vent, then back to the pump and the silica gel dryer. At some point in time, the silica gel will absorb all the moisture it can hold. This is obvious because about 5% of silica gel crystals are dyed blue that changes to a pinkish color when saturated with moisture. At that point:

Remove the saturated silica gel from the bottle
Spread it out on a cookie sheet
Heat in oven at 275^o F until the silica turns blue again
Cool and return to the bottle

Disassembled air pump. Remove the felt
filter in the bottom of the pump and plug
the hole with glue.

The frequency of this recycle rate will depend up the humidity of the environment. This may vary from months or more in dry regions down to just a week or so in the humid southeastern United States. Adding more silica gel to the bottle will extend the service interval.

Build your own

Connect the drier output via Tygon plastic tubing to the engine oil filler cap. A return line of Tygon tubing is fitted to the crankcase blow-by port. The preferred means of connection is to drill a ¼” hole in the oil filler cap and then install a short standpipe to the cap. I modified the oil filler cap by installing a hollow ¼”-20 carriage bolt. (I used a lathe to cut off the threads on the leading ½” of the bolt. This permits a slip fit of the Tygon dry air supply hose.)

The hollow bolt was then installed on the oil fill cap. Additionally, I made a ¼”-20 threaded Delrin plastic plug to cap this little standpipe during flight. Also, you will need to make an adapter to fit the crankcase blow-by tube. This can be a rubber stopper drilled to fit the Tygon return hose or a piece of rubber tubing with the return Tygon tube hot glued into it.

Please note that you will have to also devise a plug for the freeze-emergency blow-by vent located few inches up the blow-by vent pipe inside the aircraft engine nacelle. This can be a rubber flapper that normally closes the freeze vent. If the blow-by tube is frozen shut, crankcase pressure will push the rubber flap open.

The dehumidifier components consist of:

A vibrating reed “silent” type aquarium air pump
Two-liter plastic pop bottle with screw on cap
Airstone aquarium air bubbler
Ten feet of 1/8″ bore Tygon plastic aquarium tubing
Twelve inches of 3/16″ outside diameter (1/8″ inside diameter) rigid plastic tubing
One pound of 5% blue dyed silica gel
¼-20 custom air fitting hollow bolt
Pump air intake tube

Note: Low-cost aquarium pumps do have an irritating 60 Hz buzz caused by their vibrating reed design. So-called “silent” pumps are the same design but are supported in a manner that will minimize noise. If you spend a lot of time in the hangar, I strongly recommend the “silent” type pump.

To construct the dehumidifier, you will need an X-acto knife, a drill and ¼” and 3/16” drill bits, a hot glue gun, and gel super glue.

Extending the dessicant recycle time

The following modification can extend the intervals between service times for the desiccant. It revamps the dryer cycle from an open- loop system into a closed-loop. Dry air is still injected as before into the oil filler neck, but in addition, a vacuum line is attached to the crankcase blow-by tube that returns dry air back through the engine. This eliminates the continuous drying of external incoming humid air into the system and provides for continuous circulation of ever-drier air in the crankcase.

Implementation

The air pump must be converted to a blow-and-suck configuration. To do this you will need to make an additional fitting for the air intake port next to the air output port on the pump. Drill a 3/16” hole about ½” to the right of the exhaust port. Remove the felt filter in the belly of the pump case and plug the hole with glue.

Pump Return Line Installed In Blow By Port

To work as a vacuum pump, the pump case must be made airtight. This is done by disassembling the air pump case (two screws) and applying RTV silicon aquarium cement around the entire case seam and around all four sides of the power cord strain relief. Then reassemble the case and allow it to dry. Also, add RTV glue to any screw heads or tape over recess holes in the case bottom for an airtight seal.

You will also need to make an adapter fitting such as a rubber hose or rubber stopper fitted with a length of the Tygon tubing to serve as an air return to the pump.

Fabrication

Drill two 3/16” holes about ¼”off the center in the top of the bottle cap, close enough to the center to allow easy tube clearance of the bottle neck interior wall. For the pump inlet input, insert a 2” length of the rigid tubing in one hole and hot glue it into place. Insert the remaining 10” rigid tube in the other hole and hot glue it so the bottom end of the tube is positioned about 2″ from the bottom of the bottle.

Use a 1″ length of the Tygon flex tube to connect the aquarium bubbler airstone to the end of the longer rigid tubing. The Airstone is used as a dust filter to keep silica gel particles out of the engine. The airstone should lie on the bottom of the bottle.

To prep the silica gel, it in your kitchen oven at 275^oF until the dyed silica gel pellets turn blue (they are pinkish when saturated with moisture). Open the bag and pour the contents into a clean and dry two-liter pop bottle. Insert the airstone/tube assembly, work the airstone to the bottom of the silica gel, and tighten the cap. Do not delay, as it will absorb moisture from the air.

Open-loop dryer assembly

Use about a foot of the Tygon tubing to plumb the air pump to the short air input stub. Connect 6 feet or more of Tygon tubing to the airstone-equipped exit port, then to the air fitting on the oil filler cap. Connect the pump return line to the crankcase breather port via an airtight rubber seal.

Note: All connections and seals must be a leak-tight fit. Mating via the crankcase blow-by vent tube (usually located near the firewall) may be done by inserting a piece of the rigid tubing through a 3/4” closed-cell-foam ball or a tightly fitting rubber stopper.

A secondary modification required is a plug for the freeze slot in the blow by tube. This can be a rubber flap around the blow-by pipe that is normally closed over the freeze slot, but is pushed open by crankcase pressure if the exit end of blow-by tube end should freeze shut. Finally, a foam plug fitted to your aircraft’s air intake with a “REMOVE BEFORE FLIGHT” flag attached will close up the system circulation (in the case of a crankshaft position that leaves an intake valve open).

By Ryan Stark|2024-09-18T14:19:35-04:00July 18, 2023|Aircraft, Articles|Comments Off

Annual Inspection

Well, the building is over and my RV-12 is in the air. Now that I’ve got an airplane I can actually use to go places and have fun, life is a bit less hectic. Still, the fun has to stop sometime and for airplane owners, the opposite of fun is often the annual inspection. Since my aircraft is an experimental, I have to do what’s known as a condition inspection. There is maybe less paperwork involved than the annual inspection that certified aircraft have to go through, but the potential for pain is there. To be clear, this inspection is an extremely important thing to do and the pain will often be limited to just a lack of flying, though there is always the possibility that a major repair will be needed and then the pain can quickly spread to your wallet.

Inspection #2

I am actually on my second condition inspection. The first one was done in July of 2021 and it went really well. The airplane was new (only 26 hours on it), so there really weren’t any issues involving worn-out parts and other things that older aircraft have to deal with. Nope, just checking to make sure everything was working properly and all the fasteners were still holding fast.

This year has been different, but it’s not really the plane’s fault. My wife and I started the inspection in mid-July, when the weather was nice and there was still plenty of year left, but didn’t get it completely done until just last weekend (the end of January). Again, the plane is still fairly new (only at 46 hours now), so there really weren’t that many problems to address. No, this year the problem was with me. Life and work tend to have a way of keeping you busy and this year it’s been a struggle to string a few weeks together to do the inspection.

DIY maintenance

As many of you with experimental aircraft know, one of the perks of building an airplane is getting to do all of your own maintenance. No more having to find a mechanic and work around their schedule or pay their bills. The other side of the coin is, you have to do all your own maintenance. In fact, there isn’t a mechanic in this area that will touch an experimental aircraft, so I couldn’t hire this job out even if I wanted to. Thankfully, the work itself is pretty simple overall and the nice thing is there is a checklist to follow. These are printed in the maintenance manual and include a systematic checklist of everything that needs to be looked at.

I don’t think you have to be especially mechanically inclined or talented to do this job yourself, but a little mechanical knowledge probably helps. I took a 2-day class in Dallas to get a repairman certificate with an inspection rating. It was full of good information, but possibly the most important thing they did was show all the many ways people can die as a result of taking shortcuts and not following the checklist. By the time I was done with that class, I was fairly gripping the chair arms with white-knuckled fists, and ready to triple check to make sure I dotted all my i’s and crossed all my t’s.

Oil change at annual

The checklist has all kinds of things on it, and I can see how it might be tempting to skip something that seems unnecessary. One of the things on that checklist is normally an oil change. This is a standard part of most annuals and often times it’s done whether the oil actually needs changed or not. We see short-run samples like this all the time at Blackstone and often wonder if the owner is looking for a problem, or if the plane is just in for annual and this was on the list.

In my mind, if there was any one item on the inspection checklist that could be skipped, it would be an oil change that’s not needed (Blackstone’s lawyers would like to remind you that this is one man’s opinion only; officially, Blackstone advises you to follow the checklist!). Still, with that being said, an oil change is really an excellent diagnostic tool. You can send in an oil sample to see if the engine is wearing poorly and cut open the oil filter to see if it has any visual metal present. The problem with a short-run sample is, we can rarely tell the customers a lot other than there wasn’t much metal in the oil, so it looks okay from what we can see.

Unless you suspect a problem, a short-run filter inspection would also be of minimal value, for the same reason—there really isn’t enough time for any significant metal to accumulate. So how about a situation where you are halfway through a typical oil change? Where you have enough time on the oil for an analysis to tell you something, but not enough time that the oil really needs to be changed? For situations like that, you might want to get an oil sample by pulling one up via the dipstick tube. We sell a pump for just that purpose. It’s reusable and the money you’d save on an unnecessary oil change would likely pay for the pump in pretty short order.

Sampling from the filter

Or, what might be an even better option is to just change the oil filter at that point. Then you can pour an oil sample right from the filter and still cut it open to look for metal. If you do follow this route, just let us know you got the oil sample from the filter. We might see a little more insoluble (solid) material in this situation, but the metals and all other results should be basically the same as if you got the oil as it was draining out of the sump.

We understand there might be some situations where it’s not possible to stray from the checklist and it’s just easier to dump the oil and start fresh, though if you have some leeway in that regard, skipping an oil change can save some time and money, making a potentially painful job a little less so.

By Ryan Stark|2024-09-18T14:20:13-04:00July 18, 2023|Aircraft, Articles|Comments Off

Pre-Buy Samples: The Art of the (Craigslist) Deal

Taking a sample before buying a new plane or boat is common practice in the aviation and marine industries, and it’s just as useful for anyone looking for their next car, truck, or motorcycle. If you’re anything like us, you probably spend an unhealthy amount of time browsing the local classifieds and Craigslist hunting for the elusive bargain. And although oil analysis can’t stop you from making a wire transfer to your new foreign royalty business associate, it can help you avoid buying a total lemon, and maybe even calm your nerves on the initial drive home.

Pulling a sample before plunking down the dough is a good move. We’ll test the oil for excessive amounts of metal, contamination, and solids. We compare your results to our database of samples from similar makes/models, giving you a good look at how internal parts are getting along, and if there are any looming problems driving the current owner to sell you their beloved ride. We’re familiar with common problems for certain engine models and years, and we know how different issues look in analysis.

It can be tricky to gauge whether excess metals are from poor wear or from how the engine has been used, especially if you don’t know how long the oil has been run. But even if the oil was recently changed, we can still often see evidence of serious problems. Maybe coolant has just started getting into the oil, but there’s not yet enough to give the oil that telltale milkshake appearance. It takes a pretty bad internal coolant leak to cause a visual change to the oil, but it doesn’t take much coolant to show up in analysis.

You’ll also learn the oil’s viscosity range, which can show if the current owner was using the correct grade. Analysis will also pick up on things like dirt from an intake leak or excess fuel from an injector issue. We always point out any potential problems in the report comments, and try to provide possible reasons for abnormal findings in the comments to help you make sense of the results.

Sampling

Most private owners and dealerships will allow you to collect a sample, at least with a bit of persuasion. The current owner has a vested interest in the health of their vehicle, and offering a copy of a report might help even if you don’t go through with the purchase.

We sell a vacuum https://www.blackstone-labs.com/products/vacuum-pump/pump so you can take a sample through the dipstick right then and there, while you’re looking at the vehicle. Samples can also be taken by loosening the oil filter or drain plug enough for some oil to drain out — just be sure to clean the area around the sample collection point if you go this route. If a seller refuses to let you collect a sample without good reason, that alone might be the red flag that sends you running.

Getting results in a hurry

We know you’re working on a tight schedule to make the deal happen, so if you don’t have a kit on hand when you go to look at your new ride, don’t fret. You can send the oil in any clean, plastic container with a screw-on lid. Just be sure to collect enough oil for testing (about 100 mL or 3 ounces, which is a little less than half a cup), and package the sample appropriately so it doesn’t leak in transit. The same information slips included in the kits can be found on our website. We appreciate all the info we can get about a sample, as it helps make sense of the results so we can provide the best possible report in return.

Buying a used vehicle can be an adventure, and we’re here to help you make the most informed decision possible!

By Ryan Stark|2024-09-19T10:17:51-04:00July 13, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Which Oil is Best?

We get lots of questions every day here at Blackstone, and the most common question we hear (after “Do you have my sample?”) is, “What type of oil should I use?”

Because we’re an independent laboratory, we don’t recommend any specific oil brands. We always recommend using an oil grade recommended for your engine by the manufacturer and a brand that fits your budget. But beyond that, we find that brand makes very little difference. If there were an oil that consistently out-performed the rest of them, we’d have no reason to keep that information secret, but we just haven’t found that oil yet.

You can go into any mass retailer (Wal-Mart, Meijer, AutoZone, etc.) and buy a 5W/30 (or any other grade) that will perform well in your engine. One of the best-kept secrets of the oil industry is that these store brands are actually the same, quality oils that are produced by the major oil companies. The only difference between these products and the major company brands is the name on the container and the price. Don’t believe us? Try running your own experiment: do a sample on Oil A after a known number of miles, then do a sample on Oil B and compare the wear levels. You may see a little fluctuation, but it’s very rare for one oil to make a significant difference in an engine’s wear patterns.

What does Blackstone like?

But wait! We do actually have a preference when it comes to buying oils for our personal use engines. That preference however, has little to do with brand names. We tend to choose oil that does not contain sodium as an additive. Sodium is one of the markers for antifreeze contamination and when it’s present in the oil, that can make it harder to see coolant when it’s present.

What about after-market additives? Some of them contain unusual compounds that can make it difficult for our analysts to determine if your engine has a mechanical problem. One such additive contains a lead-copper compound. Both lead and copper are metals common to bearing inserts. If you’re using an additive with lead and/or copper in it, it is difficult to tell whether those elements are coming from the additive or a problem with the bearings. There’s another potassium-boron-sodium compound that can mimic coolant contamination in testing. Some of these additives linger for a few oil changes too, so even if you haven’t used them recently, they might still be affecting your oil analysis results.

If you are interested in having your engine oil analyzed, you will receive a better analysis if you avoid oil and after-market additives that use elements we need to see clearly to do a thorough analysis. If you want to use an after-market additive, that’s fine, just let us know about it on the information slip provided with the sample.

By Ryan Stark|2024-09-19T10:18:58-04:00July 13, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Soot: How Much is too Much?

Blackstone offers percent soot testing as an optional test above and beyond what we do in the standard analysis. It’s something many of our diesel customers have shown interest in. It can be challenging for people to understand how much soot is a problem and how much is normal, so in this article we’ll shed some light on our testing process and what it can tell you about the health of your engine.

Here’s a brief run-down of how it works. We use an FTIR (Fourier Transform Infrared) spectrometer to measure the percentage of soot present in an oil sample. Essentially, soot raises the absorption rate of the infrared light spectrum and when an infrared beam is shot through the sample, the rate of absorption is measured and quantified. The lab operator ensures the machine is running properly by performing a series of check standards, including calibrating against a known 2.0% soot sample to ensure accuracy.

Okay, nap-time is over. So what is soot and what impact can it have on an engine? Soot is a natural by-product of internal combustion. Soot is the reason diesel engine oil turns black, sometimes only after a few miles. When it becomes excessive it can thicken up the viscosity, leave deposits on wearing components, and ultimately clog a filter (or perhaps worse, an oil passage). Excess soot can have an abrasive component and has the ability to stick to wearing surfaces, potentially increasing oil consumption.

A used sample from a Volkswagen 2.0L TDI. Soot reads at 0.4%.

We like to see soot at 1.0% or less; anything higher than 2.0% to be cautionary. So what does that mean to you? In layman’s terms, excess soot can indicate a combustion problem. Pinpointing that problem (or problems) can be a bit more difficult, but there are a couple fairly simple things to check if you think you’re seeing excess (or just more than normal) soot in the oil. Make sure that the fuel system is maintained and properly calibrated so that the injectors are operating at peak efficiency and with a proper air/fuel ratio. Also check for intake leaks and make sure that the air filter is clean and serviceable. Make sure injection timing is set correctly as well. Change the oil and filter regularly to prevent soot build-up.

It’s always possible that excess soot is due to a mechanical problem too, and that’s obviously a bit more involved than just changing the oil or swapping out a dirty air filter. Excessive ring clearance is a common cause of excess soot. Keep an eye on oil consumption as increases in that area can also show a developing ring problem.

Several of our customers have installed by-pass filtration systems in an effort to keep soot lower and the oil cleaner in general, and that can be effective. Employing an oil analysis regimen can also be helpful in assessing wear metals and other contamination like soot…but as a Blackstone customer, you already knew that!

By Ryan Stark|2024-09-19T10:22:07-04:00July 13, 2023|Articles, Gas/Diesel Engine, Lab Tests|Comments Off