Marvel Mystery Oil

Yep, good old av gas... with lead, no doubt. Now, look at the engine, and see what sort of FAA-approved paper trail you can find that says 100LL is approved for that engine. I bet you'll find either:
A document that says 100LL is aviation gasoline, and is approved for substitution of 80 Avgas or 73 avgas.
An STC for the engine adding 100LL to the list of approved fuels.
Or other FAA-approved paperwork having the same affect.

Now I've got nothing against MMO. I've heard it praised and condemned in aviation and motorcycling and automotive circles. But I wouldn't use it as a fuel or oil additive in a certified airplane anymore than I'd use unapproved automobile upholstery material to redo the interior, or code my own GPS database for an IFR GPS.
 
Ron Levy said:
OK, then what does the type certificate say about what fuels/oils are authorized for use in that aircraft/engine? Remember, if the aircraft is not in conformance with its type certificate or in an approved altered condition, it isn't legally airworthy and 91.9 says you can't fly it. Seems to me that if the engine contains a fuel or lube product not listed in its type certificate, it's not in conformance with its type certificate. What's your basis for the approved altered condition with whatever magic elixir you choose to add to the fuel or oil?
The TCDS (or other appropriate documents) tells you what you're allowed to do in this regard. Anything else is unauthorized. The TCDS doesn't say you can't put auto fuel in the engine of this plane, either, but I'll bet the FAA will be upset if you do so without an autogas STC. Ditto putting in automotive oil. So what makes you think you can legally throw in additives not approved by the FAA for use in that engine?
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You're trying to apply Air Force logic to this situation, i.e. It has to be written or it can't be done. The TCDS for the Chief specifies "73 min. aviation octane gas." The TCDS does not state you can't add something to the gas.

As far as the engine is concerned I'm sure it states which grades of oil are acceptable (I haven't looked it up, it's fairly standard) but once again, it does not say you can't add something to the oil.

Further more there is no FAR that restricts you from putting an additive in.

Take the plexiglass windshield of your Grumman. Do you use a plexiglass wax on it? Is that plexiglass wax "FAA Approved" and does the TCDS spell out it's an approved wax, or does the wax have an STC? If not, then by using your logic it's illegal to put wax on a plexiglass windsheild.

There was a thread earlier about de ice boot treatments. Once again it would be illegal (according to you) to use the methods people were describing because it's not on the TCDS or STC'ed.
 
TMetzinger said:
But I wouldn't use it as a fuel or oil additive in a certified airplane anymore than I'd use unapproved automobile upholstery material to redo the interior, .
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Automotive interior materials meet or exceed the requirements for aviation and have for over 20 years. You can use "automotive" interior material as long as you have the required documentation to go with it.
 
Rotor&Wing said:
The TCDS for the Chief specifies "73 min. aviation octane gas." The TCDS does not state you can't add something to the gas.
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It looks to me that you could add pretty much anything you want to 100LL and as long as it meets the minimum spec for 73 octane avgas, you'd be in the clear. This of course assumes that you've already crashed the Chief and the FAA cares enough to make an issue of it to find an obsolete ASTM spec for avgas that hasn't been made for 50 years.


Trapper John
 
Rotor&Wing said:
Automotive interior materials meet or exceed the requirements for aviation and have for over 20 years. You can use "automotive" interior material as long as you have the required documentation to go with it.
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<<reply deleted, I'm going to follow my own advice.>>
 
Is TCP approved by manufacturers or the FAA, or does it fall into the same category as MMO?

I've seen it used in light sport airplanes when running on 100LL, but I'm pretty sure that Rotax specifies it.
 
Here's one for you. Who's right? The manufacturer or the FAA? The FAA has issued STC's for automotive fuel in Lycoming engines.

http://www.lycoming.com/support/publications/service-letters/pdfs/SL199.pdf

Service Letter No. L199
January 28, 1983
TO: Owners and Operators of Lycoming Reciprocating Aircraft Engines.
SUBJECT: Recommendations Regarding USE OF FUEL
This Service Letter is to clarify Lycoming’s position on the fuel grades that are specified for use in our
reciprocating engine models.
LYCOMING DOES NOT APPROVE the use of any fuel other than those aviation grades specified in our
latest edition of Service Instruction No. 1070.
OUR POSITION IS CLEAR; do not operate your aircraft on any fuel which is not specified.
 
dmccormack said:
Very interesting -- it's the most complete -- and clear -- discussion on the topic I've read so far...

Thanks for the link!
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Sounds like a lot of arm waving and wishful thinking to me.

"When it enters the combustion chamber and the gasoline ignites, it is vaporized and soaks into the carbon buildup on cumbustion chamber walls, valve guides, around the valve stem, and on the spark plug. It soaks into the carbon and eventually loosens it up and it goes out the exhaust system."

Right...
 
Capt. Geoffrey Thorpe said:
Sounds like a lot of arm waving and wishful thinking to me.

"When it enters the combustion chamber and the gasoline ignites, it is vaporized and soaks into the carbon buildup on cumbustion chamber walls, valve guides, around the valve stem, and on the spark plug. It soaks into the carbon and eventually loosens it up and it goes out the exhaust system."

Right...
Click to expand...

TCP claims the same effect... :dunno:

Why is 100LL titled "Low lead" when it 4 times the lead over 80/87?
 
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Ted DuPuis said:
Good! Go get that CFI! :)
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I'm working it, we're doing two ground lessons a week, and flying should start shortly. Right now the school doesn't have a complex, it got dinged in an accident and there's doubt if they'll replace it, particularly as the FAA is likely to remove the complex requirement for the ratings in the next 90 days. Might borrow one for my training from another pilot here on the field, if we can work out the insurance issues.
 
TMetzinger said:
I'm working it, we're doing two ground lessons a week, and flying should start shortly. Right now the school doesn't have a complex, it got dinged in an accident and there's doubt if they'll replace it, particularly as the FAA is likely to remove the complex requirement for the ratings in the next 90 days. Might borrow one for my training from another pilot here on the field, if we can work out the insurance issues.
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I had a similar problem, as the Mooney disappeared before I had a chance to get my CFI ride done. I ended up borrowing my instructor's Comanche, but that was a one-time deal. It can be remarkably difficult to find one to use. Hope you get it done soon!
 
Here's another way to use MMO that doesn't involve putting it in the gas tanks.

I had a stuck valve on an R-1340 and made a precautionary landing. We disconnected the manifold pressure gauge line, hooked a tube up to it and stuck the other end into a bottle of MMO. Ran the engine at just above idle until the MMO bottle was empty.

It makes a LOT of smoke, but seems to free up the valves. Never had another problem with a valve sticking on that engine in the next 100 or so hours that I flew it.

I'm one of the believers, especially on old engines.
 
Trapper John said:
The LL designation came from comparison to the old 100/130 avgas which had twice the lead as 100LL.
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"New 100LL AvGas! Now with 50% less lead!*"

*when compared to a fuel that had 100% more lead in the first place. Not to be confused with comparisons with a fuel with 75% less lead. Your mileage may vary. Void where prohibited. Contact your local animal control center if you suffer dizziness, nauciousness, indigestion, or pregnancy as a result of 100LL.
 
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