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

You make an excellent point. The size of the injector nozzles.

They’re continuously developing this part. Higher pressures pushed through smaller holes. Toro actually developed a high pressure injection system that would pass EPA requirements for 2 cycle engines. It required no addition environmental controls, developed higher HP ratings at lower RPMs. It went nowhere. There simply wasn’t enough interest here in the US

 

At its base, oil is oil. It’s the same if it comes out of a fuel pump or a quart jug. Refineries started by separating the oil by viscosity. Light oils like gasoline, kerosene, solvents, propane. And heavy oils like 10, 20, 30, etc weights. Then tars like what’s used in roofing and road paving. The invention behind the “diesel” engine was actually to burn coal dust. It was the oil industry that suggested using diesel, which was a bi product they considered waste.
The reason older engines fuel systems could handle 15-40 or ATF was because essentially they are the same as diesel, just heavier (on a side note, all oils have basicly the same viscosity at @250 deg). The difference between deisel, motor oil, ATF, hydraulic oil, etc is the chemical package they add to them to make them better suited for their use. They add anti-foaming adjectives to hyd oil to keep it from foaming and trapping air, detergents to motor oil to capture residue inside the crank case and drop it in the filter, even red die to ATF to help the consumer determine its transmission fluid and not motor oil.
It’s the additives that make running a quart of ATF or 15-40 in your fuel tank in today’s engines a bad idea. When the additives burn they produce chemicals the aftertreatment isn’t designed to handle.

 

Because of the larger tolerances In not only the small hard parts, but also the tolerance allowed by the EPA for clean burn and fuel efficiency. Both the tighter tolerances in the fuel systems and the chemical reactions required in exhaust treatment have transformed and limited the abilities of the “waste burning engine”

 

Lose? Hahaha Ask any of the OG that drove anything with a Detroit in it about that.

Detroit has definitely stepped up their game. But in the past....

 

I've always heard that used engine oil need to be run through a magnetic type filter to remove the ferrous metals and then through a 10 micron filter to remove the rest of the crap. These small particals could wear out a fuel or injection fump.

 

Detroits leaked oil out of every conceivable place lol. Tough as nail motors for the poor man. Most people considered them to be complete POS. But there were literally 1000’s that saw daily use through every part of the industry.

The Cat or Cummins owner would spend a week fixing an issue. A Detroit owner would use duct tape, JB weld, or bailing wire, and finish the week out. Then see if it was still holding, and work another week.

While Cat has bailed with the onset of EPA mandates. Detroit has forged a way forward. Making a new name for themselves in the industry.