Y’all running 100LL or Mogas? O-300

[mmcmillan2]

I’ve been using 100LL with no oil additives in my O-300 for the last 100-125 hrs. No valve sticking issues, but someone told me they’ll stick less if you run mogas. I have the stc, but don’t want to mess with fuel cans and stinky fuel if it ain’t worth it.

[GAHorn]

I’ve been using 100LL with no oil additives in my O-300 for the last 100-125 hrs. No valve sticking issues, but someone told me they’ll stick less if you run mogas. I have the stc, but don’t want to mess with fuel cans and stinky fuel if it ain’t worth it.

AvGas is what your airplane and engine mfr’s want you to use and it’s causing no problems for you. Your valves aren’t sticking now…so how can they “stick less”??

Non-ethanol mogas should be OK but if you don’t want “stinky gas” then don’t.

[mmcmillan2]

Thanks for the reply!

[Bruce Fenstermacher]

I can't say what the price of mogas is in your neighborhood VS 100LL. In our neck of the woods there is a $2.50 a gallon difference. The problem in our area is there is absolutely no mogas without ethanol. Otherwise I could mess with a lot of smelly mogas for the price difference.

[wabuchanan]

About a $1.10 difference in our neck of the woods. Makes it worthwhile to me. I use it all the time, but mix with LL every so often on cross country flights.

[hilltop170]

100LL avgas and non-ethanol mogas with unknown pedigree are essentially the same price in Fredericksburg, Texas. No question for me which one to use. No sticking valve issues either. I always cruise top of the green rpm and lean aggressively in the air and on the ground.

That said, years ago when I was a broke college student in the mid-1970s and leaded regular mogas was available, I ran it exclusively. I had a bootleg Westach 6-position EGT/CHT and there was absolutely no difference in either when I filled one tank with 80/87 and the other with leaded regular switching between them. I haven't run that experiment lately with 100LL and unleaded so those results might be different today.

[ghostflyer]

Ahhh. Love the smell of burnt avgas in the morning .
Used 115/145 octane purple avgas in my aeroplane once .it was only 1 tank full but found no difference in performance ,no difference in engine temperatures but it was FREE.
The wallet was heavier.

[GAHorn]

About a $1.10 difference in our neck of the woods. Makes it worthwhile to me. I use it all the time, but mix with LL every so often on cross country flights.

It’s my personal opinion that TEL (Lead) in gasoline is bad for engines. Low compression engines (like our C145/O300) does not need the octane created by the TEL…. and the old wives’ tale of lead being necessary for the valves is just that…an old wives tale. (I got rid of my Old wife and have a much better one now.).

Seriously, Lead is BAD and causes high engine wear, sludge in the sump, sticking valves (if not properly scavenged), and fouled spark plugs.

IF you can find Non-Ethanol mogas of the correct octane …then it is better for the life of our engines. (Remember when auto engines were largely worn-out at 75K-100K miles? That was before the 1980s when leaded mogas existed. When UNleaded mogas became exclusively available….. auto engines lasted 200K and More…. because we “got the lead out”.

There is NOTHING good about Lead in our fuel. So, adding half mogas and half avgas is getting the worst of both worlds….. lousy pedigree and unknowns of mogas and lousy lead in avgas.

[bugs1961]

I’ve been running mogas for the 600 hours that I’ve had my O-300 and valves look great and plugs are always clean. Something to consider:

1800 TBO x 7.5gph x $2.50/gal savings = $33,750 in fuel savings over the life of the engine. Overhaul is more than paid for.

Fortunately, there is no ethanol in Alaska so any local gas station is good to go.

I’m just about to turn over 2300 hours on my engine and there’s no sign of problems.

[N2625U]

Here in the southeast corner of New Hampshire there are no gas stations with ethanol free gas. There used to be one just across the border in Maine but the Gov of Maine dictated some years ago that only gas with ethanol will be sold to vehicles in Maine. However 2 airports within 20 miles sell Mogas but at $4.75 or $5.05/gal. Cheapest I can get 100LL is 26 miles away at $4.50/gal but I do use Mogas a lot. The $4.75/gal Mogas airport is only 10 miles away, airport I'm based at (KDAW) sells 100LL at $4.90/gal.

[c170b53]

I just filled up at $5.66 US a US gal. Its all relative but here anything under 5 is a must fill up opportunity for this guy.

[GAHorn]

I just filled up at $5.66 US a US gal. Its all relative but here anything under 5 is a must fill up opportunity for this guy.

I always suspected you were RIch!

(5.50 to $4.15 US/gal in Central Tx for self service)

[hilltop170]

…………..Seriously, Lead is BAD and causes high engine wear, sludge in the sump, sticking valves (if not properly scavenged), and fouled spark plugs…………

I must be the luckiest guy in the world. Since I started using avgas 40 years ago in every gas engine I have without a catalytic converter, I have never had a fouled plug, stuck valve, or had to rebuild an engine before TBO. And, I have never had to rebuild a carburetor or replace gaskets/seals ruined by mogas, varnish, or sludge.

Some of my engines sit idle for months and with avgas in them, I don’t worry about degradation.

Mogas is fine if you don’t let it get old, I’ve used a bunch of it in my plane and never had a problem, but it never stayed in the tanks very long.

[daedaluscan]

…………..Seriously, Lead is BAD and causes high engine wear, sludge in the sump, sticking valves (if not properly scavenged), and fouled spark plugs…………

I must be the luckiest guy in the world. Since I started using avgas 40 years ago in every gas engine I have without a catalytic converter, I have never had a fouled plug, stuck valve, or had to rebuild an engine before TBO. And, I have never had to rebuild a carburetor or replace gaskets/seals ruined by mogas, varnish, or sludge.

Some of my engines sit idle for months and with avgas in them, I don’t worry about degradation.

Mogas is fine if you don’t let it get old, I’ve used a bunch of it in my plane and never had a problem, but it never stayed in the tanks very long.

This drives me crazy. Every spring I have to strip and clean the carb on every weedeater, mower, pressure washer, etc. that I own. I try to either run them out of gas, drain them or run a tank of 100LL through them, but I don't always remember.

I run 100 LL in the plane, had one stuck valve in the O-300 (1/2 quart of ATF in each tank and it never recurred). I will use Mogas if I am low, but rarely.

[GAHorn]

[]


I must be the luckiest guy in the world..

You own a 170, a 180, a 195, a home in Alaska AND in TEXAS,… have all of US for friends…and a Fantastic Woman in love with you…. OF COURSE you are the “luckiest guy in the world!”.