Adding oil in fuel intentionally? What would be the purpose?

… struggle to flow through the filter, used engine oil will clog the filter faster.

other than that do nothing other than cause a smokey exhaust if there was enough of it.

fuel system components are designed to be lubricated and cooled by the diesel that flows through them. adding oil into the fuel tank is pointless.

on a side note, shove enough oil in the intake the engine will run on that alone. if the supply is of enough quantity it will run on it building engine RPM until, in some cases, catastrophic failure.

 

They used to dump used engine oil in tanks to get ride of the oil. You could just burn it off. Then you clogged fuel filters more. It was free and the oil would burn. They said ATF would clean the injectors. So dump a bottle in fuel tanks and clean fuel injectors.

You can't do anything like on today's new emission truck and new fuel system. You will probably destroy the high pressure fuel system they use today. Today you can buy stuff made to clean injectors. They might help a little.


Also the older engines like 1999 at later were built to run on the now old low sulfer diesel. I had a 1999 S60 Detroit and when they switched to ultra low sulfer diesel. They thought it would not lube the fuel and walls of the Pistons on the oler engine. I was adding engine back then but because I had oil sample showing I was getting more piston ring wear on the low sulfer diesel.

They solved all those problem today

 

yes, but typically only when copious amounts are fed into the intake. such as when the turbo fails and allows feed pressure into the CAC system.

youtube some diesel engine run aways, it'll raise an eyebrow

 

You could put a gallon of engine oil into a 130 gallon fuel tank and it will mix with the fuel and burn on pre emission engines. You do that today it probably clog up the DPF filter and mess up DOC filters in the emission system. Their is something in ATF fluid that will mess up the emission system. I believe the fuel pumps today have tight specs in internally also.

I ran pure 100% biodiesel in my 1999 Detroit S60 back when Bio diesel was big thing for couple years. It ran just fine no problem burning it. The fuel pump had no problems with it. It was a simple fuel pump only like $200 to replace even it it did any damage

 

Back in the day, ATF was added occasionally to soften the O rings on the injectors, so they would seal better. This was common practice in the 1970s. Did it work, or was it just a wives tale? Who knows! Some of the old miltary engines were designed to burn gasoline, diesel, kerosene and just about anything you could dump in the tank!
This was an era that had no sensors to speak of and everything was mechanical. The fuel was high sulphur and who knows what else was different in the old fuel. Today's engines/electronics would not tolerate such practices. Adding drain oil to a fuel system would plug up filters with the soot suspended in the drain oil. I think there would be codes popping up for emissions as well.

 

We used to dump it in the tanks back in the day. I wouldn’t do it with today’s engines.

We also used ATF in the winter. Supposedly to help fight gelling. But as the temps dropped even further. We dumped a half gallon of unleaded in each tank.

 

Older engines, pre-egr for sure, but mostly late 90's or older use lower fuel injection pressures and actually have larger holes in the injector tips so adding any oil to the fuel was ok and accepted practice. Actually, Cummins for one, had a system to add used oil to the fuel and burn it off. The mating parts tolerances were wide enough that any oil additives or junk in the oil would never cause a problem. Today is a very different story. Fuel injection pressures are about 3 or more times what they use to be. 33,000 psi or more! Injection part tolerances are tighter and nozzle sizes are smaller than they have ever been to accomplish this. This is why it is so important to never add anything to fuel other than a bit of winter conditioner if needed. Oil simply has too many additives that will build up and cause stiction problems or even nozzle clogging. Aftertreatment systems are also not meant to handle engines burning anything other than fuel.