I have a 2017 Silverado with the 5.3 EcoTec, approximately 81,500 miles. I'll be dropping it off at the dealership soon for diagnostics (which I don't expect much of a result from), but wanted to get some opinions from other owners as well.
The truck has never displayed any CEL codes, no starting / drivability issues or anything of the sort. But I noticed when checking my oil the last few weeks before my most recent oil change that the level on the dipstick appeared to be going up. Hard to quantify how much as it's generally a little above full after adding 8 quarts at the oil change. No milky appearance to the oil and no coolant loss, and I thought the oil looked thin and had a gasoline smell when I changed it a week or two ago. Plus my gas mileage seems to be a little worse than it normally is for this time of year. So based that layman's diagnosis and lack of an oil sample analysis, I'm pretty sure I've got gasoline getting into the crankcase.
I purposely added less oil at this last oil change to make sure that the level was in the cross-hatch section of the dipstick (even after sitting for an entire day), roughly 1/4" to 3/8" below the full mark. After putting only a few hundred miles on, the oil level is already back up around 1/4" above full.
Assuming I'm right about there being gas in the oil, I'm guessing it's either the HPFP or injector(s) to blame; most likely the HPFP since I'm not having any issues with the engine starting or running rough, and it's not throwing any codes. Is my line of thinking correct? Has anyone else had a similar experience, and if so, how did you diagnose and/or solve the problem?
I expect the dealership to tell me nothing more initially than they want to pull a sample to verify that I have fuel in the oil (and most likely to first charge me to change the oil themselves and make me drive it for a period of time before I schedule another service visit to have a sample taken). Aside from that, my bigger problem is that I just don't have much faith that they're going to be able to diagnose the issue if/when they DO verify fuel in the oil, since it's not throwing codes or having drivability issues otherwise. I have never had any luck taking things in to a dealership when there's not a CEL / code for them to diagnose. If they can't tell me with any degree of certainty, I'd rather throw parts at the problem myself than pay the dealership to do it since I'm out of warranty. Hopefully this forum can point me in the right direction if it comes to that.