@Vladimir2306
The more I read about how you drive your vehicle, the more I realize you do not drive like the majority of the people here in the US. Part of this is probably due to the roads and the amount of traffic on your roads. Traffic volume and congestion play a big factor in how a vehicle can be driven at or above the posted speed limit. I have a bridge near my house that has an average of 235,000 vehicle that cross is daily! For almost 12 hours of the day that traffic is not even running near 1/2 the posted speed limit!
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I really doubt you drive your Yukon as your "Daily" driver in the Winter months in Moscow taking 15-20 minute trips and rarely getting out on highway for extened periods of time. Additionally when you are driving your vehicle at over 100 MPH and 3000 RPM for long periods, almost anything will be "cooked" out of the oil. My truck has never seen more that maybe 1800 RPM on the highway for any extended period of time and I would bet this is the case for most owners here in the US.
Here in the US there is just no place you can easily, safetly and without dealing with law enforcement and heavy traffic run in excess of 100 MPH for hours. Too much traffic, too many trucks, too many idiots that camp out in the left lane and block traffic. Here in the US they do a poor job, if any, teaching people that the left lane is not for driving in full time and never moving out of. I drive a few routes for hours and there are always groups of 20-40 vehicles stacked up barely doing the speed limit because someone is always blocking the left lane. Rolling roadblocks is what these are called. This is TYPICAL here in the US.
I have lived in and driven in Europe for many years, and it is pretty clear you do not stay in the left lane, it is primarily for passing and in Germany you better not be in the left lane unless you are going triple digits on the speedometer and move to the right when you are not passing.
Again, I do not think you fully understand the driving, traffic and weather patterns here in the US. Because of many factors, the fuel contamination in the oil at times can become cumulative, meaning is builds up over time with shorter drives where the engine oil never gets up to even the engine coolant temperature. In many cases the engine oil in these trucks take 20-30 minutes to even reach 200F and even once the oil reaches 200F you need to keep it there for some period of time to "cook" as many of the contaminates out of the oil.
One member here that does not use his Surburan for work because it is only 9 minutes from his house and he does not want to kiil it. He has to accelerate up to close to 70 MPH almost immediately once he leaves his driveway. This can play hell on an engine with cold oil and the oil never would get much above the a 120F by the time the vehicle is shut down and this is not during Winter temps. Do this 5 days in a row and see what happens.
My wife travels 7.5 miles to and from work. The morning trip is maybe 15 minutes, but the evening return trip for the same 7.5 miles is typically 40-45 minutes. In either case, not ideal for engine oil in the long run. Luckily she does not drive a Yukon, but she still drove a vehicle with 7 quarts of oil and it would barely be warmed up on the way to work and the way home she crawled and barely was able to get car over 35 MPH. So this was clearly not an ideal situation for the engine oil.
You can have a high fuel percentange in the engine oil and still not trigger a CEL/SES/MIL codes for a rich fuel mixtures. The problem is once you are at above 2-3% fuel diluition in the engine oil, the lubricating properties of the engine oil is really starting to diminish and depending on how the vehicle is driven, this can and will become catastrophic. I have seen so much fuel in engine crankcases before where valve lifters would bleed down the engine would barely start and run.
And how are your shops determining if there is an elevated amont of fuel in the oil? Oil analysis? My last oil analysis indicated I had 1% fuel in the oil, while not a great amount or anything to be concerned about, this oil had less that 3000 miles and over 90% of the driving was done on the highway in lengths no shorter 2 hours in length. No Auto Stop/Start and DFM is disabled. I would hate to see the fuel percentage in a vehicle that was used for short, in town trip of 10-20 minutes in length with the Auto Stop/Start and DFM fully functioning along with using the remote start for engine warm ups at idle.