Just food for thought. Diesel fuel in gas tank?

[signsup]

I have no dog in this fight, just a brain fart. Recent thread on stuck valve discussed adding a little MMO to the gas tank to help lubricate valves. I have a truck driver friend that adds a little diesel fuel to every tank of gas on carb engines. Lawn tools, lawn mowers, military vehicles, etc. His thinking is the addition of a little oil with the diesel fuel at least has more combustion than MMO or other straight oil additives.
Anyone ever thought of adding a small amount of diesel fuel to the carb gas?
We only run "clean" gas in our carb vehicles, no ethynol in carb systems.

I'll hang up and listen.

[TXGOAT2]

I wouldn't do it. Diesel has a very low octane equivalency and it can attack some materials used in some gasoline fuel systems. It will attack terne plate, which was used in Model A gas tanks and perhaps late T tanks. It has very little to no lubricity. MMO, on the other hand, is a tried and true product designed for use in both crankcases and fuel systems. I have used it for decades in older vehicles with good results and no issues.

MMO costs more than diesel, but using it in the fuel as recommended saves a portion of that cost.

MMO can assist in removing combustion chamber deposits and will provide some added lubrication for rings and intake valve stems.
I have had no issues with carbon build up when using MMO as directed. It seems to reduce existing deposits.
I've had good results adding it to the crankcases of old, sludgy engines with stuck rings and/or noisy hydraulic lifters.
MMO may reduce the tendency of ethanol adulterated gasoline to decay.

[DanTreace]

No No....don't add oily fluid like diesel or motor oil in any amount to the fuel tank.

Now Marvel Mystery Oil is fine for the fuel tank, it's wintergreen oil and good for the valve stems. Place proper amount per gal. from instructions.

Once years ago thought it was a good idea to dribble a little motor oil in the tank to help the valves. Did that just before a Christmas Parade in my little home town. Well while in the line up idling, the exhaust turned blue and boils of smoke poured out......folks yelled at this youngster, so I immediately pulled out of the line and sheepishly headed home.

[schwabd1]

I’ve heard of people adding a little 2 stroke oil to their gas…..

[Craig Leach]

Synthetic racing caster oil, mixes great, will not separate, has the ability to cling to parts & smells good when it burns.
Craig.

[Pep C Strebeck]

I’ve heard of people adding a little 2 stroke oil to their gas…..

I've done that for years when starting something that has been sitting for quite a long while (log splitter, riding mower, tractor, etc.). I generally just start it using the 2 cycle gas that I have mixed for the chainsaw. Just at the startup and a little bit of run time, then back to straight gas. Once it is time to be put away again, Sta-Bil in the gas and run it to warm it up, shut it off, siphon out the tank and run it dry.

[NoelChico]

I've joined a number of folks by adding TCW-3 two-stroke oil to gas in my T's, as well as my moderns. It's designed to burn and is a top cylinder lube, decreasing piston ring friction and lubing the valve stems. Maybe it's just my imagination but I've found about 5% improved fuel economy in our RAV4 and in my F250, paying for the oil and hopefully improving engine life. 1 oz. to each 5 gallons of gas .It may also help to stabilize gas for medium length (over the winter) storage.

[Rich Eagle]

A fellow we know used to drive to and from National VMCCA tours from New Mexico in his late 20's Studebaker. He always ran a bit of diesel in the gas tank. It ran well but had more soot on the rear of the car.
I've never tried it in a T.
Rich

[TXGOAT2]

I'd do 2 stroke oil before diesel. MMO works just fine.
I've spent a good deal of money to keep motor oil out of combustion chambers. I'm not inclined to add it on purpose. Most Ts will get some crankcase oil in the combustion chambers anyhow.

People used to put Type F transmission fluid in gasoline, diesel, and in crankcases. I never heard of it doing any harm, and it did seem to help noisy hydraulic lifters and stuck engines.

I wouldn't use modern ATF... no telling what it actually is.

Some "octane enhancers" contain a substance that can damage fuel injectors. I'd be cautious about what I put in a fuel injected engine's gasoline. I've never heard of additives harming old school diesel injectors.

[Dan Hatch]

Old diesel fuel and today’s diesel are two different animals.,
Few years ago when they changed diesel fuel, it was suggested to replace the old steel tanks with either stainless or plastic.
New fuel will rust out steel tanks.

[A Whiteman]

Well a friend used to put a cap of cutting oil in the radiator of all his vintage cars and tractors. Not fuel, but still an oil additive

[George Hand]

I never got around to adding extra fluids to any of my T's, I acquired some non-synthetic snow mobile 2 cycle oil, I added a little of that to a couple of my two-cylinder John Deere tractors that set around more than the Fords, but small amounts in the tractor fuel tanks. The idea was to lubricate the valves & guides. I agree modern Diesel fuel had poor lubrication properties.

[JohnH]

Well a friend used to put a cap of cutting oil in the radiator of all his vintage cars and tractors. Not fuel, but still an oil additive

I do that, and it's a very effective rust inhibitor.

[TXGOAT2]

Cutting oil used to be pig oil with sulfur in it. It may still be. That would probably be beneficial for old diesels with mechanical injector pumps intended to run on "real" diesel, which usually has some sulfur. MMO may contain pig oil.

[Norman Kling]

I would find out which cylinder had the sticking valve and then pull out the spark plug. The valves are right under the spark plug so about 8 inches or more of wood dowel and turn the crank to the location where the valve should be closed. Then tap on it with the dowel and a very light hammer. Just enough to push the valve down. Try to push in the center so not to bend the head. If that does not allow it to drop, take a spray can of WD 40 with a long plastic tube and spray under the valve toward the stem. Allow it to run down to the guide. You could also try some liquid graphite lock lubricant in that same location. after it has time to reach the guide, tap with the dowel again. Eventually the valve should free up. If the keeper is off the spring, the valve will stay up even if it is free to move. In that case, you need to remove the valve cover to fix. I do not recommend any oil in the gas tank. It will just cause a lot of carbon and make things worse.
In California they only allow two grades of gasoline. Winter blend and Summer blend. There are 3 different octanes. The lowest octane works fine in a Model T. If you make a lot of smoke, you might get cited for polluting.
Norm

[Dan Hatch]

If this is about valves that stay up, be sure to check the valve pins and spring washers. Do a search and you’ll find a thread a few years ago about bad parts.
They would fail at a few thousand miles.