Autogas - use and personal experience

[GAHorn]

This is contrary to my personal choices in this matter, but to be completely honest about this issue, the problem with hauling autogas in one load, and avgas in another has less to do with worries of contaminating avgas than it does with concerns about contaminating mogas with lead and violating EPA and automaker warranties on catalytic converters.
An excellent example of this issue is the pipeline company I used to fly for would inform me as to the product in a particular pipeline the day I flew it, so I could identify a leak, etc., and know the product. (ICC rules required a report which included the product noted to be leaking.) Anyway, it was frequently the case that mogas would be pumped thru a pipeline from Pt. Arthur, TX to the storage facility in FtWorth, and immediately following in the same pipeline, separated only by a "pig" (a large radioactive mop to separate the product) would be avgas. They would never pump avgas followed by mogas. They always followed avgas with a short run of bulk oil or some other product to cleanse the line.
Trucking companies don't want to bother with the expense of cleaning the lead out, is my suspicion, so they haul one or the other rather than switch back and forth. This just happily allows them to carry only one product without worries of any contamination of avgas, while mogas haulers haul mogas one trip, naptha another, or whatever. (My uncle, now deceased, used to haul sulphuric acid one way, and milk the return trip. They'd steam clean the trailer between hauls.)

[flyguy]

WALL LEME TELL Y'ALL SUMPIN- - -

Every once in a while I just have to stuff him back in the bag!

The issue of using mogas in airplanes has become more complex over the years. Insurance companies, lawyers and the petroleum producers and refiners have been tweaking the system . We have been jerked around by the politicians, the EPA, MADD and whomever else wants a piece of the action, and under pressure to produce these exotic blends of fuel to meet "clean air", "clean water" and many other "new requirements" of vehicles for fuel hungry American drivers auto gasoline has taken on many different faces. MTBE additive was one of the disasters foisted off on the public then found to have a residual effect on the ground water supplys around the major cities that was unacceptable.

The problem is that major gasoline procucers have no intention of maintaining mogas integrity to the level that is mandated for consumption in an "old" aircraft engine. The pilot who uses un-approved fuel is likely to find himself in a bind with his insurer if an unscheduled landing occures and he is found with "off-air" fjuel in his tanks.

This is not to say that the stuff you buy out of the pump at your local station will not get you from point A to point B without any problem. The problems now occuring are not the same as when the push to certify mogas was underway. I have used 'car-gas' (that's what we called it before the STCs were approved) since the late '60s. I burned it in Lycomings, Continentals and a couple of round bangers and have never had a problem with the engines! REALLY!! (George just say "whoa"). I read about pilots having valves "stick" and wonder what I have done wrong! I have never stuck a valve in any enging! REALLY! (I knock on wood here!) I never put MMO in my tank or crankcase. Here is my formula. Use it or lose it!

I still use it but do not leave the stuff in the tanks for any longer than I have to. If I am not going to fly for a while I will drain the rest of the load from the tanks and fill with 100ll. I am in a unique situation here, living on a privete airport, and have no hassle in doing whatever I choose where I hangar my planes. Most folks don't have that flexibility. I have had enough problems with my boat motors to know what mogas does when left sitting in the tanks and carburetors to alert me to the possibilitythat the same thing couldhappen in my plane.

There are pros and cons but burning it and storing it (in airplane tanks and carbs) are two different issues.

[Gooney]

USE OF AUTOMOTIVE GASOLINE IN TCM AIRCRAFT ENGINES

Teledyne Continental Motors would like to remind its customers that the use of automotive fuels in TCM aircraft engines not only represents a potential safety of flight concern, but can also significantly affect cylinder life and durability.

Engines produced by TCM are FAA certificated to a minimum grade of fuel conforming to ASTM D910 - grade 100LL or 100 aviation gasoline. Early engine models such as the O-200, O-300, and O-470 series are certificated to grade 80 aviation gasoline, also conforming to ASTM D910. Detonation margins, compression ratio, rated power, engine cooling, fuel schedules, ignition timing, and fuel system vapor handling are established and FAA certificated based upon use of a fuel conforming to ASTM D910. The use of any fuel not conforming to ASTM D910 may compromise safety and/or result in significant mechanical difficulties.

Automotive gasoline is manufactured to the industry specification ASTM D4814 which does not control or establish limits for octane rating, major anti-knock constituents, or energy density (lower heating value). In addition, critical properties such as vapor pressure and level of contaminants are not tightly controlled as with AVGAS. Vapor characteristics for auto gas are inferior to AVGAS and result in a tendency for auto gas to more readily convert to vapor. In addition, the lower octane rating of auto fuel can lead to detonation and pre-ignition which may damage the engine. Alcohol content of auto fuels may also result in damage to o-rings, seals, and other elastomer components in the fuel system.

It is important to note that automotive gasolines are not subject to the high level of quality control applied to AVGAS. The allowable concentrations of additives, contaminants, and water in AVGAS are precisely controlled by ASTM D910. Automotive gasolines within the United States are changing rapidly to meet ever more demanding environmental regulations. Fuel producers have advised that auto gas will be subject to continuing changes in the future, with additive formulas varying widely. Current Federal and State laws allow properties of automotive gasoline to vary seasonally and geographically. Some states do not even require that automotive gasoline conform to the ASTM D4814 industry standard.

Current aircraft engines feature valve gear components which are designed for compatibility with the leaded ASTM D910 fuels. In such fuels, the lead acts as a lubricant, coating the contact areas between the valve, guide, and seat. The use of unleaded auto fuels with engines designed for leaded fuels can result in excessive exhaust valve seat wear due to the lack of lead. The result can be remarkable, with cylinder performance deteriorating to unacceptable levels in under 10 hours.

Field experience has determined the use of unleaded automotive gasoline to be the cause of premature cylinder replacement due primarily to rapid and severe valve seat recession. Therefore, if you choose to operate your engine on automotive gasoline, valve seat and guide wear may occur at an accelerated rate. TCM strongly advises against the use of such fuels for reliability and safety reasons. Because of this, engine or parts warranty will be voided where such fuels are used.

TCM understands the high cost of flying and is committed to the relentless pursuit of product improvements leading to improved cost effectiveness. Unleaded aviation gasoline and next generation cylinder components are integral to our strategic plan for that future. In the interim, we ask you to consider the adage of "...penny wise..." when considering the use of automotive fuels in your aircraft engine.

Well you have the info, be warned!!!!!!!!!!!!!!!!!

[zero.one.victor]

USE OF AUTOMOTIVE GASOLINE IN TCM AIRCRAFT ENGINES
................................
Current aircraft engines feature valve gear components which are designed for compatibility with the leaded ASTM D910 fuels. In such fuels, the lead acts as a lubricant, coating the contact areas between the valve, guide, and seat. The use of unleaded auto fuels with engines designed for leaded fuels can result in excessive exhaust valve seat wear due to the lack of lead. The result can be remarkable, with cylinder performance deteriorating to unacceptable levels in under 10 hours.
...............................................

George,this is why the Petersen STC recommends SOME use of avgas. You poo-poo'd the idea before,how about now that TCM makes the same claim --that leaded fuel lubricates valves/guides/seats?

Eric

[GAHorn]

This claim by TCM (and others) is the single, most-damaging flaw in their argument against mogas. (IMHO) This statement (which they persist in repeating despite widespread agreement that it is bogus) makes it very difficult for those like myself who are convinced that mogas is not good in airplanes. It destroys the engine makers and the fuel makers credibility.
Lead was never engineered into fuels because the engines had a valve problem without it. I challenge them (or anyone else) to show me any data that shows engines once-upon-a-time had a valve lubrication problem, and so the smarties over at the oil companies and car companies came up with the idea of adding lead to fuel to correct the problem. (Capital "B" and Capital "S"! The only reason lead was ever added to gas was as an anti-knock additive.)
Also, from the FAA Small Airplane Director's letter to EAA, regarding a statement from an industry newsletter making such silly claims,... " The newsletter also cited a report about aggravated engine valve seat recession (wear) with the use of autogas. Extensive FAA Technical Center testing concluded that valve seat recession with autogas use is not significantly different from avgas use." The letter was by the Manager of the FAA Directorate, Kansas City.
( http://www.autofuelstc.com/pa/faa.html ) (However, notice that this letter ignores the problems of locally available fuel quality, compatibility with aviation fuel systems over the long term, unregulated additives, altered ASTM specifications for the product, corrosion, and degraded storage life.)
The only valid argument against mogas in airplanes (again, IMHO) regards handling procedures, non-standard recipies (which damage aviation fuel system components), unreliable additive packages, corrosion and (most important)...absolutely no guarantees as to what is in the stuff you pick up at the local gas station.
Just this week (again! dammit!) I got ready to plow my garden and found my tiller carburetor and fuel tank absolutely FULL of rust, white limestone-like deposits, and water! The aluminum carb body has huge areas of dissolved voids in it, and frankly, I'm astonished that after boiling it out with solvent and cleaning the tank with acid that I was able to get the thing started and running without totally replacing the tank and carburetor! (Some of you may remember my similar problem with my Honda emergency generator.) This is on a tiller purchased new only a few years ago. I'd be willing to bet the average time between overhauls for our airplane carburetors is more than 30 years, and that most of them haven't been opened up and examined at all during the present ownership period. God only knows the condition those are in.
Now I guess I need to go look at my pressure-washer and hope to God it isn't just as destroyed from storing it with autogas.
I'll never put autogas in my airplane unless I'm being chased by the enemy, intend to burn it right away, and there's no avgas available. (I now have my equipment stored with TCP-spiked avgas.)

[zero.one.victor]

I've owned automobiles of various makes for just about 30 years now,and "mogas" has always given great service in them! Been running mostly "mogas" in my 170 for 6 years now,at least 75% by volume if not more,and again,it's performed just fine!
Seems like it's the equipment that sits idle for long periods that has problems with "mogas". My 170 doesn't do too much sitting idle,nor do my cars,so "mogas" seems to work for me.

Eric

[N1478D]

I'll never put autogas in my airplane unless I'm being chased by the enemy, intend to burn it right away, and there's no avgas available. (I now have my equipment stored with TCP-spiked avgas.)

Now come on George, you know very well that if you were being chased by the enemy, the very last thing you would jump in would be that old slow B of yours no matter what fuel it had on board. You would pick your riding lawn mower, golf cart, neighbors horse, one of your big dogs, anything that moves a little bit.

[N1478D]

http://www.eaa.org/education/fuel/index.html

A very interesting site about avgas vs mogas with reprints from good sources like LPM.

[Walker]

I have always preferred Avgas. In my little C85, I ran 80, 100LL and Mogas. With 80, the fuel system stayed tight. With 100LL, the carb would often be a little damp. With Mogas, sometimes the carb would just drip and other fittings would start to get a little wet. Aside from that, the smell of Mogas is sickening to me and the cabin would always smell of it. Marvel Mystery oil also has another nice quality. It will coat the cylinder walls and help keep the rust down. Doesn't take much.

[170C]

Thanks Joe for sharing the data via Light Plane Maint. I now have some reading to do.

This subject has been chewed on before in this forum and like Ford vs Chevy, el al. There will probably never be complete agreement. I haven't read the data Joe shared with us. I suspect a lot of it has already been made available, but I hope there may be some that is of current vintage. It would sure be nice to have available some factual results of variouss engines experience with auto fuel vs avgas without mine or others personal opinions. I don't mean that I don't appreciate all our opinions or experiences (I do enjoy and benefit from them.), but would like to see some controlled lab type results of how each fuel compares to the other in terms of maintainence, etc. Hopefully one of these days we will have some alternative to 100 LL at reasonable costs. Possibly the 82LL or something else that won't require refiners to do a lot of specialized refining just for aviation. If we could get this product, the cost should be at or near the cost of auto fuel.

[R COLLINS]

I thought I would let you know about a local airport that is selling Avgas in the East Texas area for $1.80 a gallon. It is at F44, Athens Texas, and the operator's name is Dyson Aviation. They are very friendly folks and one of the guys working there is a fellow 170 member. He is currently rebuilding a wing on his 170B, if your in the area stop in and say hello. I have seen a lot of fuel prices around the area selling fuel for $3.00+ per gallon so it pays to do a little looking around. If I had to pay that for fuel every time I flew then I would be mixing more mogas than I do now. Randal N1745D

[rudymantel]

I use car gas in my 170 unless I'm on the road. Never had a problem.
Back in 1955 I owned a Stinson 10A with a 90 hp Franklin and used car gas- worked just fine. FWIW,
Rudy

[GAHorn]

Possibly the 82LL or something else that won't require refiners to do a lot of specialized refining just for aviation. If we could get this product, the cost should be at or near the cost of auto fuel.

Don't hold your breath, Frank. Autogas at airports isn't at the cost of auto fuel obtained at service stations. With the oil companies claims of covering special handling, cleanliness, liability, etc., I'll bet it'll be pretty much the same kind of prices above mogas that we already are paying.

[170C]

Yea George, you are unfortunately probably correct.

See you at the Texas 170 Christmas party!!!!!!

[AR Dave]

What is the recent wholesale gasoline price in California?
Is it over a $1?
What is the recent gasoline tax in California + Fed?
Is it under $1.50?

We are now sending less than 1/2 production from Alaska. Ya'll just keep voting Oil Production out of America and see where the price of gasoline goes too. Don't anyone from California even get me started