Reg. or premium??

I'm new to this forum. But love most anything related to Allis Chalmers. My question is should I run premium gas all the time in my 49 B. It does not seem to  "mind" the regular stuff . Just curious  what everyone else runs. I do add some  stabil additive cause my B  may sit for in its shed for months .Thanks for your  advice. 

I use 89 because it doesn't contain the ethanol like the 87 does.  93 is over kill in my opinion.

Thats what i thought all gas sold in MN has 10% or greater ethonol added except for Av-gas or some racing fuel .

Around here (near the Boondocks) 87 octane fuel is unleaded, no ethanol. 89 is E10.

Gerald J.

Ethanol doesn't turn to acid.  Its hygroscopic, meaning it attracts and absorbs water, almost its entire weight which is both a good thing and a bad thing. 

There is ALWAYS water in fuel.  For years, people in the snowbelt have used HEET to deice fuel,  its ethanol.  If you use a tractor/vehicle regularly and refill the tank with some frequency, their is no harm(maybe a plus) in using fuel with ethanol.  The ethonol keeps the water in suspension and allows it to be run thought the engine with very little worry of slugging the carb. 

The problem comes to when you let it set.  In a tractors fuel system, which is vented to air, moisture laden air is brought into the tank with every cooling cycle (at night).  The alcohol absorbs it.  After it absorbs so much it starts to settle and separate from the gasoline. (Phase separation)  After it absorbs its own weight in water, it still attracts water but can not hold anymore and separates into a water layer on bottom, then alcohol, then gasoline.  The water then slugs the fuel system(crappy running) and rust the tank if its steel. Some rubbers are affected but fuel lines made in the last 20 years are formulated to resist it so I don't think it to much of a trouble as fuel lines should have been replaced by now anyways. 

Thanks for explaining the ethanol. I am still going to run the RV fuel in my stuff because it really does seem to run better. I don't farm so I really don't use that much. I won't tell my friend as I don't need an argument!

Premium gas (93 octane), whether with ethanol or not, burns slower than "regular" (87 octane) gas, which is why it helps to prevent knocks in some engines, usually large V-8's.