mogas

[NSEMN8R 0]

It looks like we're going to have ethanol free auto gas available to us next season. My plane already has the stc for it, but I've never actually tried it.

It costs 4.15/gal vs. 5.65 for 100LL.

Anyone know of any reason I shouldn't use it?

Anyone using it with good results?

Thanks in advance.

[jonstark 8]

If you're running a big bore Continental with compressions of 7:1 it will like it a lot. You may find your fuel consumption goes up slightly though. A good/legal fuel handling trailer will be a cost to consider. I figure it'd take about 4000 gallons for us to break even but the advantage is not having to taxi across the field to tank up then have to fly heavy. I'd be able to add a few gallons and fly lighter and skip the trip to the FBO pumps. Very tempting. BTW it is stinky! You don't even need to have a seep, sweat or leak in the fuel system to smell Mogas all over. 100LL doesn't do this nearly as bad.

jon

[Ron 10]

My plane has the STC for mogas.... My mechanic said that it is not as good for the engine and that the engine needs some lead to lubricate and reduce wear.

I have had several other mechanics support that first opinion. Based on the information I was given, I have not tried to use it.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[theonlyski 8]

There are actually several companies out there working on a lead free AVGAS replacement, though I'm not sure what the difference between the new 100 and the old 100LL as far as lubricating goes. I do know that they are having to test it to certify it for existing airframe/engines, but I don't know if there is a modification required to the aircraft to run it.

I do know a couple of pilots that used to run MOGAS in one tank and AVGAS in the other. Use the AVGAS tank for start up, taxi and take off, switch to MOGAS for cruise and switch back for landing.

The issue that caused one of them to never even consider it again is a vapor lock shortly after rotation (he luckily had runway available and power off landed without incident). The MOGAS is more likely to vaporlock (I believe it was the lower octane of it).

ETA: http://www.aopa.org/News-and-Video/All-News/2013/December/3/shell-unleaded.aspx?WT.mc_sect=tts&WT.mc_id=131206epilot

Quote

Shell reveals unleaded avgas
New formula 10 years in the making

December 3, 2013

By Jim Moore
Shell has been working for a decade in a dedicated aviation laboratory developing an unleaded aviation fuel. Photo courtesy of Shell.
Shell has been working for a decade in a dedicated aviation laboratory developing an unleaded aviation fuel. Photo courtesy of Shell.

Shell Aviation, a subsidiary of the multinational oil giant Royal Dutch Shell, announced Dec. 3 that a 10-year effort in the laboratory has produced a fuel that may put a long-sought goal—once thought to be unattainable—within reach: a lead-free “performance drop-in” replacement for 100LL that could power any aircraft in the piston fleet.

“That’s our definite goal,” said Michael Sargeant, avgas commercial aviation manager for Shell Aviation, in a phone interview, when asked specifically about the ambition to produce a “performance drop-in” avgas replacement. “We’ve tested it and had some exciting and successful tests.”

The lead-free formulation has a motor octane number (MON) over 100, a critical factor in formulating a fleetwide fuel that could power high-compression engines. (Octane prevents premature ignition known as detonation, and is measured by more than one scale.) Shell’s new lead-free formula has passed preliminary tests in Lycoming engines on the ground, and a Piper Saratoga recently flew for about an hour on the fuel, according to a news release from Shell—the first of many tests that will be required for certification.

“It’s an exciting milestone,” Sargeant said, adding that the company looks forward to working with manufacturers across the general aviation industry, and various regulatory agencies. The company will pursue fleetwide certification rather than a model-by-model approach. Sargeant said tests done on the new formula to date “indicate that it’s a great candidate for fleetwide approval.”

The exact path that Shell must navigate to gain such approval remains to be established. The FAA has a goal of deploying a lead-free piston aviation fuel by 2018, though Sargeant said the company may be able to achieve required approvals and start distribution sooner than that.
Shell is the first major oil company to announce an unleaded avgas formulation. File photo.
Shell is the first major oil company to announce an unleaded avgas formulation. File photo.

“We believe two to three years might be possible,” Sargeant said. “That’s the timeframe that we would love to work towards. The details need to be developed.”

Sargeant said another design goal is to keep the retail price similar to avgas, though it is too early to know exactly what the new fuel would sell for. Shell has only just begun conversations with the various regulatory agencies involved. The fuel will be submitted for approval from the FAA, ASTM, and the European Aviation Safety Agency.

“AOPA welcomes Shell’s announcement of their development of a lead-free potential replacement for avgas and their engagement of the aviation industry,” said AOPA Vice President of Regulatory Affairs Rob Hackman. “We look forward to learning more about Shell’s fuel and efforts as they work with ASTM, FAA, and EASA to achieve the approvals needed to ensure the safe operations of the general aviation fleet.”

Lycoming Engines Senior Vice President and General Manager Michael Kraft praised Shell’s effort in a news release:

“They engaged Lycoming to test their fuel on our highest octane demand engine and we can confirm that it’s remarkably close to Avgas 100LL from a performance perspective,” Kraft said. “This initiative is a major step in the right direction for general aviation.”
Shell’s new unleaded aviation fuel has been tested successfully in Piper aircraft. Photo courtesy of Shell.
Shell’s new unleaded aviation fuel has been tested successfully in Piper aircraft. Photo courtesy of Shell.

Shell is now among three companies that have announced unleaded formulations that could replace avgas in piston aircraft in a matter of just a few years, pending additional testing and regulatory approval. Shell is by far the largest of the companies known to be developing unleaded aviation gasoline. Sargeant said that Shell’s research team has been focused on finding a single fuel that can work for all, rather than a multi-fuel approach with different formulations to meet varying engine requirements.

“The industry doesn’t need bifurcation,” Sargeant said, noting that the company envisions making it possible by licensing or other means for other petroleum producers to manufacture and distribute the formula, which is made from existing components and will not require major changes to the production and distribution infrastructure.

“We think the secret going forward is really working with as many experts as possible,” Sargeant said.

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
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[CSpenceFLY 1]

You might want to take into consideration your relationship with the airport authority and the FBO before you start hauling in gas from off field. Sometimes, no matter how great you think it is having skydivers on the field, fuel sales are the only thing standing between them looking for a reason to get rid of your ass.

[dzswoop717 5]

One problem with mogas is it's short storage life compared to avgas. Mogas turns to crap in a month or two.
But if you only buy what you need and don't leave it in your plane for too long before flying it, it can work fine.

These old Cessnas were built to fly on 80 octane. The engine will run fine as long as you take the extra care to keep fresh fuel in your plane.

There are also quit a few guys who use mogas that put a little Marvel Mystery Oil in with every fill up. These guys swear by it.

I have also heard that mogas is harder on the fuel cells and fuel lines. I never used it long enough to see if this was true.

We have a gas station half a mile away from our airport that sells ethanol free fuel. I use it in my Light sport but can't use it in my 206. Everybody on our airport that has a plane with an auto fuel stc buys and flies this fuel with no problems that I have been made aware of.

I have heard that it is not legal to use in a commercial operation. I have never read the regs to see if this is true.

[theplummeter 15]

Our dropzone has the STC and runs mogas in a 1957 Cessna 182 with an O-470 (standard, non Pponk).

We just shut down early for the season as somehow unadvertised Ethanol made it into the 91 octane mogas we purchase and destroyed all of the seals in the carb.

Prior to that we have run it for two years saving a ton of money. We always top off at the end of the day with 100LL to preserve the fuel, keep the valve train leaded, and show the airport some fuel money love.

[wolfriverjoe 1,523]

Ron

My plane has the STC for mogas.... My mechanic said that it is not as good for the engine and that the engine needs some lead to lubricate and reduce wear.

I have had several other mechanics support that first opinion. Based on the information I was given, I have not tried to use it.

I would suggest your mechanics do some actual research. The "Lead In Avgas" myth has been around for a long time.

And it was debunked a while back.

FAA Letter:
http://www.eaa.org/autofuel/images/letter-2.pdf

EAA article on operation after an overhaul:

http://www.eaa.org/autofuel/faqs/engine_overhaul.asp#TopOfPage

From the article:

Quote

Experience has shown greater extended life, and more time between overhauls, with the use of unleaded automobile gasoline.

There is a suggestion to use 100LL for the first 10 hours after a Top Overhaul to deposit a small amount of lead. But after that, it's uneccessary.

My old DZ ran 2 182s exclusively on AutoGas. No notable problems. We also had our own tank, which would sit partially filled over the winter. No issues with the gas in it come spring.

To the OP: Read through the EAA site on AutoGas. They jumped through all the hoops with the FAA to get it approved back in the 80s. It was a very long and involved process. Thousands of hours of testing. Dozens of engines run for long periods of time and then torn down and inspected. It was not a "rubber stamp" approval.

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