Autogas STC

[avbug]

The TCDS is referring to a different standard and method of determining octane...your TCDS octane value doesn't necessarily correspond to the octane rating you see at the pump for MOGAS.

You're better off filling up with Avgas if the airplane is going to sit, and no, mixing avgas and auto fuel isn't going to hurt...other than making the fuel mixture less stable for long term storage..and putting your system at risk of gumming up. (varnish).

Getting an STC doesn't do anything other than give you a bit of paper that says you're legal. That's all. You still need it, but don't think for a minute you're buying more than legality, because you're not.

 

[USMCmech]

A well written article examining the pros and cons of Mogas

http://www.avweb.com/news/maint/187232-1.html

The few pilots I have met who used Mogas reported few problems, but I have hear a lot of other people say that it is terrible.

 

[aucfi]

Very good article; answered a ton of questions that I would have never thought of or considered. Thanks for sharing.

 

[FlyingToIST]

The previous owner of my PA28-151 put a MOGAS STC on it. This actually allows you to mix the fuels as well. You can put 10 gals of avgas on top of the 7 MOGAS you had and vice versa. The thought of running something cheaper was really tempting at first but my mechanic and few others i talked to discouraged me from doing so..

 

[sleddriver77]

Again, you MUST get the STC before you fill up from the Mogas pump.

Must you? For most of the small, low-compression piston engines that are covered by this STC (which is held by EAA) the extent of the changes which must be made to the engine in order to comply with the STC is: Placing a band around a pushrod tube to indicate that that aircraft has been STC'd. (In other words; that you sent a check to EAA to pay for a copy of the STC, and helped reimburse EAA the cost of driving around in their "research" Skyhawk full of car gas for awhile, and now you have the paperwork to prove it.)

IS car gas a good alternative? Probably not. Can it cause detonation, vapor lock, and other problems that AvGas would not? Sometimes. Are you 100% sure of what you're buying at the Car Gas pump? Absouletely not. State and local emissions requirements, and therefore percentages of additives, vary- A LOT. Will running Car Gas eventually eat the seals in your carburetor, fuel tanks and hoses? You Betcha. Will most small piston singles fall out of the sky if you burn car gas now and again. Probably not. If you're gonna run car gas now and again, SHOULD you get the STC? Yup. All it takes is some Fed with an AutoGas hard-on to see you dumping a gallon of unleaded into your airplane and come over and ask if you have the STC.

My $0.02

sleddriver; A&P/IA, EAA member, ATP, and poor dumb sumbitch who, on more than one occasion, has landed on a road for car gas out of necessity. (Alaska and Canada)