Fuel Dilution in the Oil , Running Rich ?
 

I got my used oil analysis back today, it showed fuel dilution in the motor oil of 3.4 percent which tends to be high. In the past it was never above 1 percent. Not sure is causing the unburned excess fuel, car running rich ? , or a stuck injector. The car runs well, no CELs to report, no dark smoke out the rear under hard acceleration. My 02 sensor is pretty low mileage, fairly new still, spark plugs are new, coils are low mileage and seem to be working well. Injectors were cleaned and flow tested about 2 years ago, I always use Shell V-power fuel.

Any ideas on what might cause the excess fuel ?, thanks for any replies.

Normally associated with wear on the rings. Are you N/A, Blown or Squeezed? Which lab did the work......Blackstone? Are you using the labs baseline or do you have analysis history on this motor?

Utah

Thanks for th reply.
Well, we just put in a new block (used with 60k miles), the old block self-destructed. We put in new piston rings, all new bearings, oil pump, and seals. The old pistons were cleaned and re-used. The cylinders/block has 60k miles on it, but the cylinders were in great shape. This is the first analysis since the new setup. The analysis was done by Toromont/CAT labs. The old motor never had more than 1% fuel if I recall, I had a couple reports done prior to it blowing up. The motor is NA.

Iron and Aluminum wear metals were up compared to past reports but I kind of expected that on the first OCI, bearing metals were low though.

Maybe I need more miles on this to break in the rings/cylinders some more ?