2 cycle oil as a diesel fuel additive ?

[wgtoys]

I had a quart of the water cooled (boat) engine type 2 cycle oil I wanted to use up. Having heard of many people burning used motor oil in their diesel engines, I thought that I would try an experiment with my 50 year old MF TO35 diesel tractor with a 4 cylinder Continental diesel engine. The engine was rebuilt at least once over 10 years ago before I got it. I put 50-100 hours per year on the tough old bird.

Recently I was getting a lot of leakage around the seals of the fuel injection pump. This is about the most expensive part on one of these engines with replacements in the $500-$1000 range. My surprise is that with the 2 cycle oil dosed into the diesel fuel at a 1:32 ratio (following the bottle instructions as if I were blending 2 cycle fuel) the injection pump stopped leaking. Previously it was doing the drip, drip, drip thing while running, but after about 2 hours of use with the 2 cycle oil blended in the drip stopped.

Could it be that the modern diesel fuel is incompatible with this old girl? Obviously today's diesel fuel is a much different animal than that which was pumped in 1957! Perhaps the old stuff had greater lubricity????

I'm not getting any hint of black smoke from the exhaust and now I'm thinking that I might be buying more 2 stroke oil when this bottle is used up.

Comments?

 

[unDummy]

Lean it out. You risk carbon buildp.

1oz per 5 gallons improves gas lubricity. This is recommended dose for UCL's like Lucas, MMO, FP60....in a gas engine.
With a diesel, I don't see why you couldn't go richer but why waste money? Try dosing 1 oz per gallon.
I wouldn't be surprised if a diesel can run on 2-stroke oil all by itself.

With a diesel, a fuel additive should always be used. Most will improve lubricity and keep the fuel system clean.

 

[Shaman]

I think that you are experiencing what alot of ULSD users are experiencing. The fuel changes, and causes leaks or worse. If the 2 cycle works, and you don't have problems, go for it. Alot of guys are dosing with Bio or canola to get the seals back down to normal with ULSD.

 

[Blue99]

Well, it sounds like the 32 to 1 ratio was what the seals/gaskets needed to absorb some oil and reverse the effects of aging.

Rubber can typically be mixed or blended with a process oil & the years of exposure to diesel fuel evidently leached the some of the oil out of the rubber gasket & caused it to fail.

 

[mechtech2]

I thought that diesel fuel was a pretty good lubricant compared to gasoline -especially gas with alcohol in it. This has been postulated as why diesel engines last so long.
I use a little 2 stroke oil in my street car's gas.

 

[wgtoys]

Thanks for the replies. I think I will keep doing what I have been doing. Google searching ULSD shows up lots of conversations about issues with reduced lubricity of this new blend. It seems that there is very little I am likely to do to harm this old engine using the 2 stroke dose and much good.

I wonder why the fuel standards don't require that the same level of lubricity be maintained while reducing sulfur content? Obviously from all of the additives being sold there are a number of ways of doing so.