Best gasoline to use in a M38A1

[Deadguyllc]

Does anyone know? They only had leaded gas back in 1952, when my Jeep was made.

 

[FireFighterHill]

HowStuffWorks "How Gasoline Works" Alittle knowledge goes a long way. The lowest octane at the pump in texas is probably 87 or 89 right? Unless your running high compression or some kind of power adder like a super charger or a turbo the lowest octane pump gas will be fine.

 

[steelypip]

Given that you're talking about a 1950s battlefield-ready tactical truck that was expected to run anywhere in the world, I think the best gasoline to use in an M38A1 is probably liquid.

Most engines with those design criteria have a minimum RON of about 75 or so, which would equate to a PON of around 73. The lowest you can buy in the US is higher than 80 and higher is better.

 

[cbvet]

I understand Fred Ropkey, at the Ropkey Armor Museum, has been running aviation gas in the older vehicles for years with no problems.

 

[DieselBob]

Most likely the only real issue you might run into over time is the ethanol (alcohol) in current gasoline likes to turn non-alcohol rated hoses, seals and some gaskets into a brown slimy goo. The ideal gasoline to use would be 100LL av-gas. It doesn't contain the crap ethanol and still has a very small amount lead to boost the octane rating. Big problem is that it's not road legal.

 

[stumps]

The ethanol is super easy to remove, add a cup of water to a 5 gallon jug of gas, and give it a shake. Let it settle overnight, and the ethanol will all end up in the water blob on the bottom of the can. Pour off anything that isn't in the water on the bottom into your good gas can..

-Chuck

 

[DieselBob]

The ethanol is super easy to remove, add a cup of water to a 5 gallon jug of gas, and give it a shake. Let it settle overnight, and the ethanol will all end up in the water blob on the bottom of the can. Pour off anything that isn't in the water on the bottom into your good gas can..

-Chuck

Thanks for the information Chuck. I never thought about the water bonding to the ethanol and staying that way. I knew that the main ingredient in most gasoline drying additives was alcohol but never gave a thought to using water to get rid of it.

 

[stumps]

If you buy one of the testing kits the marine guys use to check for alcohol percentage, that is how they do it. They have a little vial with markings that show how much water to start out with. After adding the water, you fill the vial the rest of the way with gasoline, cap it, and shake it up. If there is ethanol, the "water" level will rise. The vials are marked in percentage ethanol for 10%, 20%, and 85%.

-Chuck

 

[velociT]

AVGas is leaded, no?

 

[quickfarms]

There is a special type of avgas that has lead and is lo octain.

The issue with using avgas is the highway tax is not paid on it.

You will probably have to get the airport to fill up the 5 gallon cans then dump it into the jeep.

It is used in boats a lot because the ethonol will eat the fiberglass tanks.

I run high quality 89 octain gas in my M38a1.

You may have to rebuild the carburator if you have any issues.

I think the kit made by midwest is ethonol compatable

 

[M813A1]

Yes aviation gas is still leaded in some grades !! The best bet is to run the Rgeular Unleaded and add a lead subtitue into the tank . THAT ENGINE WILL HAVE TROUBLES WITH THE CARB IF YOU RUN ETHANOL FOR TO LONG !! IT WILL DRY OUT THE RUBBER AND NEOPREME PARTS AND CAUSE PROBLEMS !! Remember the 1970's when the ethanol gas was call gasohol is sucked then and it sucks NOW !!! ity is all a scam by the oil companies and the Politicians in Washington !!

 

[emmado22]

SEF-94 is the stuff to use. Not cheap, but good stuff...

 

[quickfarms]

What is "SEF-94"?

 

[ProviderDriver]

SEF-94 is the stuff to use. Not cheap, but good stuff...

SEF-94 is a 94 Octane motor gas by VP Racing Fuels. no ethanol


I was going to say that and I agree. The VP Racing fuels I sell at work have a non-ethanol 94 octane unleaded, as well as a couple leaded grades. I would look into that. The only grade of AvGas that is cracked and blended today is 100LL. It has about 4 times the amount of lead that is in the old "regular" leaded gas. I would run 100LL with Alcor TCP it is a lead softener that softens the lead buildup on the valves and plugs of lower compression engines so that it can be blown out the exhaust. It will look like gray powder/soot in the pipe. I would also throw some MMO in the crankcase and fuel tank. 100LL was designed for engines over 9:1 compression. the old 80 octane Avgas was for the lower compression engines. Once 80 was phased out, we had no choice but to ruin a 100 dollar set of plugs every 25 hours unless we doped the gas with Alcor TCP.

 

[68t]

I run the cheapest gas, i can find in my halftracks and ww2 vehicles with no problems. I run 87 in every thing i got. I save the alcohol for me, it make me run better.

 

[jamesfrom180]

I remember reading up on hardened valve seats. I do not have the time to look it up but I believe it is a concern with both the L and F heads. My poor jeep has been re-powered.

I remove the ethanol from pump gas. I mix any additives into a jerry can and drive around till the main tank needs a fill up. That way it is all good and mixed up. I actually just use the Stabil brand ethanol remover. I store my jeep idle for weeks and don't get a chance to turn it over so I like the stabilizer in the gas.

 

[stumps]

I remember reading up on hardened valve seats. I do not have the time to look it up but I believe it is a concern with both the L and F heads. My poor jeep has been re-powered.

I remove the ethanol from pump gas. I mix any additives into a jerry can and drive around till the main tank needs a fill up. That way it is all good and mixed up. I actually just use the Stabil brand ethanol remover. I store my jeep idle for weeks and don't get a chance to turn it over so I like the stabilizer in the gas.

Ever since lead was first removed from gasoline, there have been those that have said that without the lead to act as a cushion, the engine will destroy the valve seats. I have numerous engines from the days before unleaded gas was even a dream that I have worked long and hard while burning unleaded gas without showing any signs of valve seat problems. I think the doom-and-gloom over lead removal was just hocum. I have seen only positive results from burning unleaded gasoline. Spark plugs last longer, valves stay cleaner, the oil stays cleaner, and the exhaust pipe stays cleaner. I like that.

Ethanol, however has been killing my engines. It hardens some rubber parts in fuel pumps and carburetors, and makes other parts swell. Float valves with rubber tips stick in their seats starving the engine of gasoline after you start, and the poppet valves in fuel pumps stick open making the pump not pump. Yuch!

If you check the ingredient lists on virtually all of the gasoline additives like Stabil, you will find alcohol.... and gasoline. I doubt that any of the additives will improve the situation, and suspect that most will actually make it worse.... I have had some luck with Stabil in preventing gasoline from going sour, however.

I first figured out how to remove ethanol alcohol from gasoline when I noticed that any of my small lawn mower engines that had float bowl vents wouldn't start after they sat for a couple of weeks. When I took them apart I would find a puddle of brown water in the bottom of the float bowl... and in the tank... just enough to keep the engine from firing. Clean out the water, and they would start right up.

In the course of cleaning up the water mess, I noticed something strange. If I put some fresh E10 gasoline in a pan, it would almost instantly get really cold, and haze up. After several minutes, brown globs of water would settle out to the bottom of the pan. What was happening was the alcohol was drawing the moisture out of the air, and when the water load got too high for the ethanol, it settled out... little blobs of unburnable gorp in my gasoline.

If you want to remove the ethanol from your gasoline, put a 1/2 cup of water into a gallon jug, and fill it the rest of the way with gasoline. Screw the cap on, and give it a shake. Let it settle for a few hours, or over night, and all of the ethanol, and ETBA will be settled out on the bottom of the jug. Pour off the clean gasoline, and repeat. No need to add any more water, as the 1/2 cup will draw out a lot of ethanol.

The down side to this method is the ethanol adds some octane to the gasoline, and removing it will make it a sub regular gasoline. Your lawnmower, or jeep won't care.

-Chuck

 

[dodgedougak]

The only problem with taking the ethanol out of the gas is that you just lost 10% of what you paid for. This ethanol thing is going to be a political football before it is over. I believe in a Personal Right to blend my fuel, not a Gubment mandated blend!

 

[stumps]

The only problem with taking the ethanol out of the gas is that you just lost 10% of what you paid for. This ethanol thing is going to be a political football before it is over. I believe in a Personal Right to blend my fuel, not a Gubment mandated blend!

I can't say that I like being forced to throw away 10% of the gas I paid for, but on the other hand, I really hate having to repair the carburetors every time I use my low usage engines (chippers, tillers, etc...)

My daily driver has a gas mileage meter on it, and I noticed an interesting thing: When I burn E10, I get 10% less gas mileage than when I burn ethanol free gasoline. As I see it, the ethanol is going along for the ride, but is contributing nothing to the power generation from my engine.

-Chuck

 

[jamesfrom180]

The way I understand the use the ethanol is really just a filler or extender. Has very little to no fuel value in most engines. Anyone know of this for fact or bs?