Auto Fuel STC

[maxine_]

Has any of you guys heard about this Auto Fuel STC? What are your thoughts on this?

 

[Raymo]

There isn't an "auto fuel" STC that I am aware (auto fuel includes Ethanol). Petersen, Swift Fuels and GAMI all offer STCs. the one from Petersen, if you aircraft meets requirements, allows the use of non-Ethanol fuel (aka MOGAS). The one from the other two allow the use of their specific fuels, though SwiftFuels also includes future approved fuels, if that happens.

 

[greentips]

Has any of you guys heard about this Auto Fuel STC? What are your thoughts on this?

I have the Petersen STC and have used it in my C182 for 30 years without an issue. If you are in Michigan, you have to hunt a bit to find it as very few, if any, gas stations have it readily available. The EAA offers a similar one and both run about $1.50 per HP to get the STC. Some Piper PA28 variants cannot use it, while others can. I think that most non-injected, non-turbocharged Cessna airframe/engine combinations can get it.

As for my experiences, I've never had an issue with mogas on the road at airports who still offer it. Many have dropped it over the years and the airport managers I've talked to don't have a consistent or solid reason for dropping it. In Minnesota it's available everywhere at local gas stations as many boat owners, snowmobilers and aircraft owners use ETOH free 91 octane mogas. I have a friend whose mechanic told him he could just run any gas and the ETOH didn't matter. I took an some old gas cap o-rings and put it in a mason jar with 100LL for a day, a second in a jar with ETOH free 87 octane mogas, and a third in 10% ETOH mogas which tested to about 8% ethanol. The results: caliper diameter of the 100LL and ETOH free samples were identical and at the pre-test size. The 8% ETOH o-ring was about 15% larger than the other two and did not fit the gas cap, let alone seal the tank. Don't use ETOH laden fuel, no matter what the concentration is.

When I had my O470R overhauled at 1700 past its 1500 hour TBO, the engine builder called me and asked how I kept the engine so clean. I ran Phillips XC, and probably 80% of the hours on mogas. In its early days I ran AVGAS 80 until it disappeared. The current run is at 200 past TBO with good compressions, borescope inspection shows very little to no wear, oil analysis shows no significant wear metals. The first run overhaul did show wear metals which led to a more comprehensive 100 hour inspection and wear on the #5 cam lobes. The only significant change in operating procedures on the second run is I've started using Camguard about 1400 hours SMOH, so we'll see. I fly between 75 and 200 hours a year, so the airplane is flown regularly, mostly on long distance trips near maximum range (4-5) at between 4000 and 14000 ft. I've noticed no difference in burn rates or indicated airspeed rates. My engine is on the cold blooded side and runs CHTs in the low 300s to upper 290s at cruise, leaned. When 80 went away, I was burning a steady diet of 100LL and had to pull the plugs every 100 hours or so and pick the lead out of them, and thoroughly clean them to keep the engine running well. This went away with the use of mogas. I have fuel bladders replaced over 15 years ago and with more than 7000 gallons of mogas through them without a problem.

 

[DNeuf]

Has any of you guys heard about this Auto Fuel STC? What are your thoughts on this?

I have run none ethanol fuel for over 20 years without a single issue in a 172A. Just make sure you test the fuel for ethanol which is easy to do. It takes two minutes. As posted above, cleaner plugs... and better for the engine than 100LL for "low compression" engines 8.5 to 1 and lower.
If there is no auto-fuel STC for your plane, I would not run it. Vapor lock issues may be a problem if your airframe does not qualify.

 

[Toga Cruiser]

I have the Petersen STC and have used it in my C182 for 30 years without an issue. If you are in Michigan, you have to hunt a bit to find it as very few, if any, gas stations have it readily available. The EAA offers a similar one and both run about $1.50 per HP to get the STC. Some Piper PA28 variants cannot use it, while others can. I think that most non-injected, non-turbocharged Cessna airframe/engine combinations can get it.

As for my experiences, I've never had an issue with mogas on the road at airports who still offer it. Many have dropped it over the years and the airport managers I've talked to don't have a consistent or solid reason for dropping it. In Minnesota it's available everywhere at local gas stations as many boat owners, snowmobilers and aircraft owners use ETOH free 91 octane mogas. I have a friend whose mechanic told him he could just run any gas and the ETOH didn't matter. I took an some old gas cap o-rings and put it in a mason jar with 100LL for a day, a second in a jar with ETOH free 87 octane mogas, and a third in 10% ETOH mogas which tested to about 8% ethanol. The results: caliper diameter of the 100LL and ETOH free samples were identical and at the pre-test size. The 8% ETOH o-ring was about 15% larger than the other two and did not fit the gas cap, let alone seal the tank. Don't use ETOH laden fuel, no matter what the concentration is.

When I had my O470R overhauled at 1700 past its 1500 hour TBO, the engine builder called me and asked how I kept the engine so clean. I ran Phillips XC, and probably 80% of the hours on mogas. In its early days I ran AVGAS 80 until it disappeared. The current run is at 200 past TBO with good compressions, borescope inspection shows very little to no wear, oil analysis shows no significant wear metals. The first run overhaul did show wear metals which led to a more comprehensive 100 hour inspection and wear on the #5 cam lobes. The only significant change in operating procedures on the second run is I've started using Camguard about 1400 hours SMOH, so we'll see. I fly between 75 and 200 hours a year, so the airplane is flown regularly, mostly on long distance trips near maximum range (4-5) at between 4000 and 14000 ft. I've noticed no difference in burn rates or indicated airspeed rates. My engine is on the cold blooded side and runs CHTs in the low 300s to upper 290s at cruise, leaned. When 80 went away, I was burning a steady diet of 100LL and had to pull the plugs every 100 hours or so and pick the lead out of them, and thoroughly clean them to keep the engine running well. This went away with the use of mogas. I have fuel bladders replaced over 15 years ago and with more than 7000 gallons of mogas through them without a problem.

Great post even if a few months old on auto-fuel. I have had very similar results with my 182 with the o470S.
Your question about FBOs dropping it I have an opinion. First obtaining it and quality control are issues. The major aviation fuel suppliers provide the FBO with trucks and credit card readers and instant credit check ability. Plus the FBO can turn anywhere from 1 to 4 dollars a gallon on avgas and pennys on autofuel.

When auto fuel first came out and for years it was bad mouthed by FBO mechanics who blamed it for every unrelated problem a plane might have. I went into a FBO shop one day and ask for a front fuel strainer cartridge as the rubber tip came off mine. First words out of mechanics mouth was Car gas?

So auto fuel does not have the quality control after it reach’s the airport ,there is no money in it and it competes too much with their high dollar high profit fuel.

 

[greentips]

Great post even if a few months old on auto-fuel. I have had very similar results with my 182 with the o470S.
Your question about FBOs dropping it I have an opinion. First obtaining it and quality control are issues. The major aviation fuel suppliers provide the FBO with trucks and credit card readers and instant credit check ability. Plus the FBO can turn anywhere from 1 to 4 dollars a gallon on avgas and pennys on autofuel.

When auto fuel first came out and for years it was bad mouthed by FBO mechanics who blamed it for every unrelated problem a plane might have. I went into a FBO shop one day and ask for a front fuel strainer cartridge as the rubber tip came off mine. First words out of mechanics mouth was Car gas?

So auto fuel does not have the quality control after it reach’s the airport ,there is no money in it and it competes too much with their high dollar high profit fuel.

I'm not sure how the quality control of mogas can be any different after it reaches the airport than 100LL or any other fuel they handle. The procedures are identical. The storage tank inspections and filter changes are the same, as are the storage and handling conditions.

It does compete with their high dollar, high profit fuel and very well. They can set a price well below 100LL and still have a bigger margin than they make on 100LL. This could put their fuel at a price point below airports carrying avfuel exclusively, make flying more economical for pilots, resulting in increased hours flow and more fuel sales. At airports away, when I can find mogas, it is frequently between $0.50 and 1.50 below 100LL.

With the lobbying for lead free fuel these days, having mogas on the field setting the same or lower price with similar margin & volume considerations could be a PR advantage both within the airport/aviation community and the sponsor's community. That appears to be especially true in California these days.

 

[Toga Cruiser]

First of all I’m on your side and I have used auto fuel in my planes for 40 years even before it was legal. I wish all airports had it. It would cut our cost in half.

Here is a few facts though. No major avgas suppliers that I know and I have a good friend in the business will put avgas in their trucks or fuel farm. Not saying it does not happen but he has not seen it.
Avgas is filtered in and out of the suppliers tanks. Then it is filtered in and out of the airport fuel farm. Then it is filtered in and out of the truck.

Mogas is brought to the airport by a local Joes fuel service and dumped into a tank and is filtered by a spin on filter on a gas pump just like on the farm. That’s fine with me . There may even be fuel trucks that have mogas but probably bought locally. Some suppliers don’t check it that well for ethanol and most do. You should check each fill yourself.

Auto gas especially in the last few years has a short shelf life compared to 100LL.

There is only one company that makes lead any more for 100LL and and only one refinery built for it since 1988.

My airport sells the new no lead fuel in their main tanks but it cost more than 100LL per gallon.

You make some very good points about mogas keeping the price of competing fuel lower. I hope it works. Did you here that a major refinery maybe the only one in California announced they are shutting down a leaving the state thanks to Gavin’s proclamations on EV’s?
I still buy my fuel at a station in 5 gallon jugs. Wawa gas stations even carry 100LL in some locations. I always run it thru a tractor funnel with a chamois filter and have found sand and silt looking stuff in it a few times from WaWa.

 

[greentips]

First of all I’m on your side and I have used auto fuel in my planes for 40 years even before it was legal. I wish all airports had it. It would cut our cost in half.

Here is a few facts though. No major avgas suppliers that I know and I have a good friend in the business will put avgas in their trucks or fuel farm. Not saying it does not happen but he has not seen it.
Avgas is filtered in and out of the suppliers tanks. Then it is filtered in and out of the airport fuel farm. Then it is filtered in and out of the truck.

Mogas is brought to the airport by a local Joes fuel service and dumped into a tank and is filtered by a spin on filter on a gas pump just like on the farm. That’s fine with me . There may even be fuel trucks that have mogas but probably bought locally. Some suppliers don’t check it that well for ethanol and most do. You should check each fill yourself.

Auto gas especially in the last few years has a short shelf life compared to 100LL.

There is only one company that makes lead any more for 100LL and and only one refinery built for it since 1988.

My airport sells the new no lead fuel in their main tanks but it cost more than 100LL per gallon.

You make some very good points about mogas keeping the price of competing fuel lower. I hope it works. Did you here that a major refinery maybe the only one in California announced they are shutting down a leaving the state thanks to Gavin’s proclamations on EV’s?
I still buy my fuel at a station in 5 gallon jugs. Wawa gas stations even carry 100LL in some locations. I always run it thru a tractor funnel with a chamois filter and have found sand and silt looking stuff in it a few times from WaWa.

Likewise. I put a JM Ellsworth 55 gallon transfer tank in the truck bed certified for gasoline by the DoT with a pump and filter, nozzles and high quality grounded hoses. It comes with a State DoT certification as well. I use that spin on filter and a view glass to observe sediment, water or other non organic solvents. I used to use the plastic jugs, but hauling up 36# at a time 8 times was no fun. The meter just clicked over its 9000th gallon. So, on the whole, I'm pretty satisfied with the quality of mogas I put in the plane. Michigan used to label the pump gas with the percent alcohol until Jennifer Granholm was elected governor. She eliminated the mandatory label on the pump if there was any alcohol. Now she's Secretary of Energy and doing just about as well there as she did in Michigan. I have no faith in pump gas there, but do know select suppliers who do carry alcohol free gas, most of them are flyers with aircraft.

I spent 40 years in Ann Arbor, and know the owner of a national Avgas supplier well, very well in fact. You are correct. Avfuel suppliers will not put mogas in their fuel farms and they are offering to provide tanks for their fuel, locking the FBOs into their brand at their prices. But there is nothing from stopping the airports from putting it in their tanks and many did and some still do. I buy most of my avgas and airport mogas at self serve tanks which never sees a truck after delivery, so that eliminates the airport truck issues. Most airports I do business with have self serve credit card pumps these days and I don't mind pumping my own gas.

It is interesting to watch California send business to Nevada, Texas and Arizona. And ban fuel imports.

 

[Toga Cruiser]

I like your idea of a tank in your truck. I think I will shop around for a set up like you have. It is getting more difficult at my age to climb a ladder. But I think I will still use my tractor funnel idea.

One last thought and I’ll hush about auto fuel. I thought I would ask the friend of mine in the av gas business why there is not more mo gas availability at airports.
He thought a few seconds and what he said was a shocker to me. He said mogas only makes up for about 2 percent of general aviation fuel-sales. He said it’s such a small market they don’t even concern themselves with it.