Got my oil analyzed and it said 'excessive fuel dilution change oil'. I only had 2K mileage on the oil when analyzed. Anyone ever run into this? What causes this? How to fix? A little concerned because oil filters cant filter fuel out of the oil.

Jim D
90 vert

 

Well, the sign of fuel in the oil "excessive amounts that is" is a sign of worn oil regulator rings or possible a leaky injector. However, if you got your oil analyzed at a company that test piston engines than re-think that test. Remember are oil system is different than a piston engine. Use a thick viscosity oil and change it regularly. Every 2,500 to 3,500 miles.

 

I have changed my oil a few times and it smelled bad like gas. There are a few post about this, and no one seems to really have a solid answer. I know that a car that floods or sits up will do this as the oil seals will shrink up a bit and not seal as well hence gas getting into the oil stream. I wouldnt be too concerned but keep an eye out for excessive smoking.

 

#1 oil filters don't filter out fuel.

#2 the oil should be changed every time the engine has been flooded. That will stop 90% of the fuel smell and dilution in the oil if there are no mechanical problems.

 

Thanks for the info. What are 'oil regulator rings'? Oh, BTW, I use Castrol GTX 20W/50 since car was new in 1990 and it now has 142K. Change oil @ 3000 miles until a couple years ago, but when I started smelling the fuel in the oil, I switched to oil intervals to every 2000 miles.

As for the oil analysis concerning piston engines-vs-rotary, whats the difference? Oil is oil, right.