Those of you who use mogas have you had any issues?

narchee

narchee

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Long Blinker
I'm always interested in the discussion around using mogas and finding a plane with STC that allows it. The benefits are obvious, but what about the drawbacks? So the lower octane requires low compression I get that but what about the higher volatility of mogas? Do any of you using it have issues with high temperatures or high altitudes? How easy/hard are they to hot start?
 
I haven't had any real issues with my Grumman AA1. On a really hot day after shutting down it can get some vapor in the line. The way around this is to cycle the fuel pump a few seconds before trying to prime or start and the issue goes away. I have never had a problem starting in the summer. I fill two 5 gallon jugs every time I head to the airport. Mogas is about 1/2 what current 100LL prices are in my area so the savings add up. I fly about 100 hrs a year give or take and it saves me $1,750.00. Enough to cover hanger rent and about half of my annual cost.
 
I have racked up over 1200 hours on my present engine burning MoGas. Well, not 100% MoGas. I try to shoot for a 66% to 75% mix of MoGas to AvGas. That's what my engine likes. No issues.

That blend also happens to put the lead content near the levels of the old 80 Octane AvGas...and at what my engine was designed to burn.

About the only "issue" is that you can see more varnishing when you look inside the engine from the MoGas than there would be if I were burning 100% AvGas. But this hasn't caused any problems.

You don't have to burn 100% MoGas just because you have the STC. You can find a blend that makes you and your engine happiest.
 
I fly to the Bahamas a lot, and the airport I fly into does not have any fuel, I have wondered if I could top off regular gas to mix with my avgas just to be sure I get back to the US. They don't even offer Mogas over there, I have not tried it, but often take over two 5 gal cans of avgas, which is a violation , but rather face a ramp check than run empty. My engine is a 260 Lycoming, any advice on mixing,,,
 
Does your engine/airframe combination qualify for the MoGas STC?

Can you get quality conrolled 0E MoGas there?

If the answer to either is no, then I wouldn't.
 
I've run a lot of mogas through an E-225 engine, an O-320 engine, and an O-200. All ran a bit better on mogas than 100LL. The E-225 runs a little smoother and cooler. I don't know the chemistry enough to say why, but it is so. Economy, or consumption, or however you want to measure it seems to be the same, or slightly better. Lead deposits are gone of course, and although it does smell worse, I get used to it.
 
I witnessed a fatal accident a few years ago, student and CFI. Aircraft engine ,65hp., stumbled on takeoff stalled , crashed, CFI died, student was badly injured. As I recall it had old car gas in it plus lousy looking plugs. Apparently old car gas is a bad thing to use.( over 3-4 months) I never used it. Especially with ethanol in it. I did use car gas in my Stearman, high test but gas was cheap then and the compression on the Stearman was very low. No ethnol back then in the 80s.
 
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I had a forced landing in the late 70's or early 80's (would need to check my logs) in a properly STC'd PA28-151. The mechanic attributed it to vapor lock due to mogas. High OAT, full tanks, a/c sat out in the sun prior to departure.

On a related note, I sat in on an airport board meeting a couple years ago. The board was considering mogas for the airport. Two mechanics with (conservatively) 60 years of experience between them cautioned against it, based on their experiences.

The board still cut a deal with a local dealer to keep a mogas truck at the airport. Since then, their truck full of 'new' mogas has turned into 'old' mogas, as no one really bought much of it. Within the last couple weeks, the truck left the airport. I have to wonder what became of the 'experienced' mogas, as well as being concerned about the folks who actually fuelled their a/c with it in the last few months.

Mogas is 'like a box of chocolates'.... YMMV....

Jim
 
I use it all the time. No problembo.

A co-worked used E-10 in his aircraft with aircraft grade fuel lines that swelled shut and shut his engine down shortly after takeoff.

A Beech Sport that I had flown at one time went down and according to the NTSB the cause was auto fuel (there was no STC for the Sport). However, some people might feel that the maintenance on that particular aircraft was not all it should have been.
 
Jim Rosenow said:
I had a forced landing in the late 70's or early 80's (would need to check my logs) in a properly STC'd PA28-151. The mechanic attributed it to vapor lock due to mogas. High OAT, full tanks, a/c sat out in the sun prior to departure.

On a related note, I sat in on an airport board meeting a couple years ago. The board was considering mogas for the airport. Two mechanics with (conservatively) 60 years of experience between them cautioned against it, based on their experiences.

The board still cut a deal with a local dealer to keep a mogas truck at the airport. Since then, their truck full of 'new' mogas has turned into 'old' mogas, as no one really bought much of it. Within the last couple weeks, the truck left the airport. I have to wonder what became of the 'experienced' mogas, as well as being concerned about the folks who actually fuelled their a/c with it in the last few months.

Mogas is 'like a box of chocolates'.... YMMV....

Jim
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Interesting.

I've always thought there has GOT to be a catch (there is usually no free lunch). Why else would there have been decades of development with Avgas that resulted in lower vapor pressure being required? Avgas was developed for a wide range of flying conditions some of you using Mogas may not be seeing. I'm just trying to understand what that new range is.
 
narchee said:
Interesting.

I've always thought there has GOT to be a catch (there is usually no free lunch). Why else would there have been decades of development with Avgas that resulted in lower vapor pressure being required? Avgas was developed for a wide range of flying conditions some of you using Mogas may not be seeing. I'm just trying to understand what that new range is.
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Depends on the airplane. Some have vapor pressure issues and are not good candidates for auto fuel, some do not.
 
narchee said:
Interesting.

I've always thought there has GOT to be a catch (there is usually no free lunch). Why else would there have been decades of development with Avgas that resulted in lower vapor pressure being required? Avgas was developed for a wide range of flying conditions some of you using Mogas may not be seeing. I'm just trying to understand what that new range is.
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I spoke with a chemist at one of the Oklahoma refineries about 8 years ago. He said the vapor pressurization difference shouldn't be an issue unless you get into the oxygen levels. I try to maintain at least 25% avgas in my tanks so I don't worry about it. I also don't get into the oxygen levels.

Then again, if you don't fly much and have the wrong formulation in your tanks for the season, I could see that creating problems. Don't know that for a fact though.
 
I have lots of problems in the pawnee. Every time I put any 100LL in it I have to clean plugs every few days. I try to use 100% mogas. Ditto for the champ.
 
Not a problem in my Continental A75 at all. I always fill it with Mogas using 5 gallon gas cans when I'm at the home airport. When I'm cross country I usually always end up buying 100LL. I can't really tell a difference as to how it runs on either.

I'm not plagued by lead issues since I'm mostly mogas, which is a pretty nice benefit.

For the engines that don't mind, mogas works great. If you can get a STC then you're not going to have any problems else the STC wouldn't exist.
 
Does anyone have a mogas stc pirep on the PA-28-180,-181? I know Peterson sells one but I have never heard of one installed and flown.
 
timwinters said:
About the only "issue" is that you can see more varnishing when you look inside the engine from the MoGas than there would be if I were burning 100% AvGas.
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Got a reference for that?
 
timwinters said:
I spoke with a chemist at one of the Oklahoma refineries about 8 years ago. He said the vapor pressurization difference shouldn't be an issue unless you get into the oxygen levels. I try to maintain at least 25% avgas in my tanks so I don't worry about it. I also don't get into the oxygen levels.
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What are oxygen levels, and how does one get into them?
 
bahama flier said:
I fly to the Bahamas a lot, and the airport I fly into does not have any fuel, I have wondered if I could top off regular gas to mix with my avgas just to be sure I get back to the US. They don't even offer Mogas over there, I have not tried it, but often take over two 5 gal cans of avgas, which is a violation , but rather face a ramp check than run empty. My engine is a 260 Lycoming, any advice on mixing,,,
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Why wouldn't you stop for fuel at a different bahama airport?
 
NoHeat said:
What are oxygen levels, and how does one get into them?
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push the black and blue levers forward, roll in a little nose-up trim

btw I have seen vapor lock problems with mogas in the high teens but that was in an E/AB. If you have a factory built plane with a mogas STC, the STC testing should have covered the altitude capability of your airplane.
 
I use mogas almost daily unless I'm driving the diesel. ;)

Finding the ethanol free variety for the airplane is difficult around here though. We do run it whenever we feel like tanker it it over from one of two locations in the entire Metro area that has it.

No significant problems running it in either the ground based transportation units or the airplane. :)
 
I ran over 12,000 gallons of mogas through my O-540-powered Pathfinder, without a burp. That engine was clean as a whistle, and compressions were awesome.

I've been running 100LL exclusively in our O-360 powered RV for over a year. I've had fouled plugs, a sticky valve, and the borescope shows an engine that is chock full of carbon and lead.

I'm in the process of building another fuel truck, and will be burning mogas again in a month. I've had enough of this over-priced, crappy 100LL fuel!
 
Not a problem here, try to run MOGAS exclusively, however I get to use, in reality, about 95% of the time. I fly an FD CTLS.

Cheers
 
weirdjim said:
The only problem I've had is finding it. Gasahol just doesn't cut it in the Cessna.

Jim
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Yeah, there's not much availability in CA at all from what I've seen on the websites showing where it can be had. Here in MO it's hit and miss. Some areas (near lakes) have it everywhere. Other areas are 0E deserts. We have but one station in our area selling it but that one station is convenient for me, thankfully, as it's almost right on the way to the airport.
 
weirdjim said:
You mean you didn't bring Purple Passion with you?

Jim
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Ha! That was the "Mighty Grape", my first mogas fuel truck. (It was a purple Nissan that eventually broke in half due to rust.)

The version I brought here was "The Green Grape", a green Toyota T-100. When I sold it, I stupidly gave the tank/pump away, because I couldn't find any unpolluted car gas.

Now that I've found a good source of unpolluted car gas, I need to make a new rig for my F-150.
 
narchee said:
I'm always interested in the discussion around using mogas and finding a plane with STC that allows it. The benefits are obvious, but what about the drawbacks? So the lower octane requires low compression I get that but what about the higher volatility of mogas? Do any of you using it have issues with high temperatures or high altitudes? How easy/hard are they to hot start?
Click to expand...

The main drawback to MoGas is the volatility, the greatest problem with it is the short shelf life and high solids residues it leaves in fuel tanks, lines, and fittings.

The plane has to prove out a couple of hot fuel climbs to gain the STC.
 
bahama flier said:
I fly to the Bahamas a lot, and the airport I fly into does not have any fuel, I have wondered if I could top off regular gas to mix with my avgas just to be sure I get back to the US. They don't even offer Mogas over there, I have not tried it, but often take over two 5 gal cans of avgas, which is a violation , but rather face a ramp check than run empty. My engine is a 260 Lycoming, any advice on mixing,,,
Click to expand...

Yes. Much better to put in 10-20 gallons of MoGas than haul gas cans in the cabin. Just pour it in on top of the 100LL.
 
I don't have many hours under my belt, so my thoughts may not count for much, but for what it's worth, pretty much all of my 100 hours have been in mogas powered aircraft. The school where I trained and where I continued to rent uses mogas exclusively in their C150s, C172, PA28, Apache, Ercoupe, and C140. I have flown all but the C140 in temperatures from 20°Fto 105°F without any problems at all. All of those are low compression 4 bangers, so I don't yet know first hand how some of the larger 6 cyl engines do. I just bought a 182 and I will be getting the STC for it very soon and will be hauling gas from the pump in a 60 gallon truck bed tank that will be plumbed into the trucks factory fuel tank. This way, I can have a good volume of gas on hand, but I won't have to worry about shelf life since I'll be drawing some of it off to run the truck and refreshing it regularly. I may have to buy a tank or two of 100LL until I get set up, but I'm looking forward to using the mogas, and from everything I've read and seen, I don't anticipate any issues in the 182.
 
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My airplane, which used to sit all winter (field was not plowed), has been operating on mostly auto fuel at least since the last owner bought it. Now that I own it, it usually flys a few times over the winter (but not this winter).

I've seen no trace of problems in the fuel tanks (which I have had out for other reasons), gascolator, carb bowls, or anywhere else.
 
Its almost as far for fuel from my location to a fuel station in the Bahamas as it is back to US.
 
OkieFlyer said:
I don't have many hours under my belt, so my thoughts may not count for much, but for what it's worth, pretty much all of my 100 hours have been in mogas powered aircraft. The school where I trained and where I continued to rent uses mogas exclusively in their C150s, C172, PA28, Apache, Ercoupe, and C140. I have flown all but the C140 in temperatures from 20°Fto 105°F without any problems at all. All of those are low compression 4 bangers, so I don't yet know first hand how some of the larger 6 cyl engines do. I just bought a 182 and I will be getting the STC for it very soon and will be hauling gas from the pump in a 60 gallon truck bed tank that will be plumbed into the trucks factory fuel tank. This way, I can have a good volume of gas on hand, but I won't have to worry about shelf life since I'll be drawing some of it off to run the truck and refreshing it regularly. I may have to buy a tank or two of 100LL until I get set up, but I'm looking forward to using the mogas, and from everything I've read and seen, I don't anticipate any issues in the 182.
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One thing I recommend to people who regularly run MoGas is that if you are going to park it for a while, drain the system and put some 100LL in it (if you don't have bladders, you can just leave it dry.)
 
Henning said:
One thing I recommend to people who regularly run MoGas is that if you are going to park it for a while, drain the system and put some 100LL in it (if you don't have bladders, you can just leave it dry.)
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not just drain and fill, but also run it long enough to fill the carb bowl with 100LL
 
JHW said:
not just drain and fill, but also run it long enough to fill the carb bowl with 100LL
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Personally I'd prefer to leave the carb/FI system dry, just leave a couple gallons of 100LL in each bladder to keep the vapor level up.
 
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