You don't have to mix anything if you don't want. The ethanol in todays pump gas is rough on modern rubbers and will eat up old style rubber parts in no time at all. These rubber parts that you should be concerned with are the diaphragms in the carb and the pump and any other rubber hises or seals in the fuel system. Ethanol is designed to be burned in mdern engines that run at much higher temps then our old engines and burn or boil the majority of the ethanol out of the engine. Our cold running engines do not and this leaves a dirty sticky residue on internal parts that causes excessive wear and restriction over time. This should help you understand why today's pump gas is not the best for your engine.
Avgas does not contain ethanol and actually contains real lead that our engines really like because the lead cools, lubes our valve stems and prevents detonation. Since Avgas is expensive it may not be cost effective to run it all alone. Therefore we suggest you mis the avgas to your pump gas at say 1 part avgas and 3 parts pump gas. The lead helps and the thinning of the ethanol helps. In the continental US the Avgas only comes in one flavor today. 100LL which is dyed blue. So for every 8 gallons of ethanol pump gas you use throw in 2 gallons of avgas and enjoy the ride.
I've read this stuff is designed for steady rpm engines. BS?
Yes that is BS. It is designed for use with the higher compression ratios found on aircraft hi performance piston engines.
So an airport will sell this fuel to just anyone? Our airport in town lists 3 companies at the airfield who sell Avgas (currently listed at $4.80/gallon).
Who the airport sells gas to is up to them. I would suggest you carry your can up to the pump and tell them you need some 100LL for your buddy's homebuilt aircraft project which has a 360 HP Lycoming IO360.
I started mixing 115/145 Octane Avgas with Auto gas in the mid 60's. The good ole days back then we had a choice of 115/145, 100, or 80 octane avgas all with lead. We lost 115/145 in the 80's and we lost 80 in the mid 90's.
Off road RV and aviation fuel supplies do not have the road tax on them in most states which is why you must be careful how you ask to have your gas can filled.
So running the 100LL avgas straight is ok if you can afford it or we should mix it to lower the octane level? What harm does the higher octane levels cause on our mv?
No, mix it. Straight 100LL will quickly lead foul valve stems and even plugs. It will burn a bit hotter and the risk of burned exhaust valves is higher.
So if there are no road taxes on Avgas and it is dyed blue, if I use it in my jeep on public roads (mixed with unleaded fuel from the local gas station) will it get me into trouble (but when was the last time that I got pulled over that the police ask to see the fuel in my tank)?
Thanks,
Kendall
Actually the blue dye is the giveaway. They don't have to look in the tank. They can look at the carb throat or just look for the blue stains wherever the gas dripped.
The brain dead crooks back in the 60's that tried to run the 115/145 Octane avgas we had on base for the old piston aircraft in their cars were often caught at the base gate with the purple stains.
The "E10" ethanol blend is lousy for our old low compression engines.Here's what I use in the 87 octane pump gas with excellent results in my M38; a product called "Star Tron". This was developed for marine engines to combat the harmful effects of ethanol. It is an additive, like "Stabil",only better,designed for ethanol. It is a Must for carbuerated engines,as the ethanol is highly corrosive to diecast & steel ( carbs,fuel tanks,lines) Please check it out, it's sold at motorcycle,boat,equipment dealers. Star Tron.com Also,I replace my mechanical fuel pump with a low pressure ( 4-7 psi) electric pump on a dedicated circuit. This lets you shut off the pump & run the carb dry,keeping the carb from corroding. and avoiding having the mechanical pump diaphram leak from the ethanol blend. Check it out!
Ethanol is a problem for pre 1970 engines but it is a manageable problem. I don't feel the extremes such as electric fuel pumps and emptying carbs between uses are necessary. In fact from a corrosion standpoint most testing facilities report the corrosion becomes an issue when the parts are exposed to air. This means empty of fuel. I feel marketed elixars are at most questionable. My answer for the last 20 years has been add back a quantity of lead in higher octane gas (100LL Avgas) to reduce the harmful concentration levels of the oxygenates such as ethanol. Using modern seal and diaphragm materials is essential. Draining and exposing components to air is only safe to do if you then immediately coat the components with a preservative such as 10 weight oil. This is especially true in steel fuel tanks which you will notice are usually corroded through the upper portions first because we do not keep the tanks full all the time to keep air from them.
So my advice when making any important choice in life is to get the THE WHOLE STORY disect and understand what you read then make your best choice.
Here is an excellent discussion of " Star Tron" fuel additive and its benefits by guys who have old Military vehicles; G503.com message forums "Star Tron fuel additive".As Wes says,research the issue,and make your choice...
I'm heading over to the airport pump in the morning.
I've decided I want to run my jeep and my old '74 two stroke on the 3:1 mix using 100LL and 87 at the pump. I currently run 91 in the bike so I figure the mix will be about the same.
I would rather mix it at 50/50 if price is the only issue. I'd rather pay the extra cost then rebuild my carb and fuel pump.
