Fuel in the oil

[NELLY1947]

This was a real surprise... I have a 2023 Yukon XL Denali with a 6.2. I decided to get my oil analyzed due to the engine recall out there and no real solution at this point except installing a thicker grade of oil. Well I got back the report and not had a chance to speak.to anyone at the lab yet but it states "4.1% fuel in the oil".
I thought the oil seemed thin when they gave me the sample. Anyone have an idea hiw this could happen?? How dangerous is this? As in BOOOM?? or seizure ??

 

[Fless]

You might want to look at your fuel trims to see if it's over-fueling.

 

[swathdiver]

This was a real surprise... I have a 2023 Yukon XL Denali with a 6.2. I decided to get my oil analyzed due to the engine recall out there and no real solution at this point except installing a thicker grade of oil. Well I got back the report and not had a chance to speak.to anyone at the lab yet but it states "4.1% fuel in the oil".
I thought the oil seemed thin when they gave me the sample. Anyone have an idea hiw this could happen?? How dangerous is this? As in BOOOM?? or seizure ??

Lots of city driving and or idling. Take her out on the highway for an hour and most of it will evaporate.

 

[blanchard7684]

long oil change intervals will do that...and also it is the nature of direct injection.

 

[jfoj]

Short drives and a lot of starting and stopping. Are you allowing the Auto Stop/Start to operate all the time or do you disable it?

In case you were unaware it takes these engines about 20 minutes of driving before the engine oil fully warms up. The engine coolant temperature has nothing to do with the engine oil temperature. Search my user name, I have plenty of graphs of engine oil temp warm up curves.

I do not run 0W20 engine oil in my vehicles, it offers no margin or threshold for fuel dilution and is offers marginal protection for the 6.2l based on engine bearing loads. Suggest you run 0W40 oil, it will not be a problem.

Depending on your driving conditions, a few suggestions.

1. Make sure you drive at least 15-20 minutes minimum every time you start the engine, in the Winter months, at least 25 minutes. Try to get the vehicle on the highway every week as well.

2. Turn off the Auto Stop/Start feature every time you get in the vehicle.

3. Put the transmission in L9. This is fine up to 55 MPH, if you plan on a highway trip, move to Drive, but L9 is fine for in town and short highway trips. This keeps the DFM from operating.

4. Change your engine oil long before the OML indicates it needs to be changed, recommend changing the engine oil around 60% OLM indicator.

5. Run 0W40 engine oil. Check the oil every 1-2 fill ups for proper fill level. These engines really need 9 quarts of engine oil, there will be a lot of trash talk about this, I really do not care, pay careful attention to the dipstick level and make sure you fill to the top of the hash marks on the dipstick.

 

[Antonm]

You either need to change your driving habits, or change your oil more often.

Fuel dilution above 2% in gasoline engines is bad (diesel's can handle a little more), especially when you're starting out with 0W20 oil, which is the bare minimum oil that'll get the job done.

But if that oil analysis showed acceptable levels of lead, tin, and copper, then you likely have no damage to the bearings as a result. Still not a good idea to run around at 4% fuel dilution though, just means you got away with it this time.

Post up a copy of the oil analysis results (with any personally identifiable information blacked out of course)
...

 

[NELLY1947]

Well here is the update.. 2800 miles since the last oil change. last time used mobile 1 . 0-40 as suggested by the dealer. one excuse they used was if I did a lot of stopping and starting with small trips. well this time I did 2 hours of hiway at 70 mph. the oil was so hot the guys asked "if I boiled it first" . well guess what 4.6% fuel on the oil. this is now 15000 moles and the 6th oil change. any one have some real input. HELP

 

[blanchard7684]

Check fuel trims to see if ecm is pulling back on injectors to keep o2 readings in line. 4% fuel…That has to be a leaky injector.

 

[jfoj]

Keep in mind that even driving on the highway and getting the oil up to temp may not fully cook off all the fuel in the oil, but that being said you have a pretty high level still after driving on the highway prior to the oil change.

So I am spit balling a bit here.

A few things, as mentioned get and OBDII tool and monitor the fuel trims and see if there are any clues.

I assume you are not using the Auto Stop/Start feature (ASS)??

My gut tells me your high pressure fuel pump may be leaking internally into the engine from from the high pressure drive shaft?? Not sure if you can get the dealer to check this and cover under warranty?? You may need to agree to pay to pull the high pressure fuel pump to check for leakage around the shaft, I think this is about 1 1/2 of labor. Assume if you are under warranty coverage if the dealer finds the high pressure fuel pump to be leaking, then they would cover even the "removal for inspection"??

Earlier models were recalled for this type of problem and high pressure fuel pump shaft leakage is not unheard of.

Other things to check could be the butterfly at the input to he muffler to make sure it is not stuck, air filter, MAF reading on OBDII scan tool.

Still slightly concerned about short trips, but this is still a very high fuel dilution percentage even for short trip driving. I could see this during the Winter months in temps under 40F and you driving short tips of less than 10 miles in town with allowing the truck to cool off between trips. You only have 15000 miles on a 2023 so you probably either do not drive the vehicle daily or drive short distances.

How many miles do you typically drive each day?

Do some searching on line for GM V8 high pressure fuel pump leaks into the crankcase, this is not a rare problem, but has not risen to the point of being recalled. Generally the recalls regarding the high pressure fuel pumps have been due to external leaks and fire concerns. Internal fuel leaks into the engine would not typically be recalled unless the leak is enough to cause the oil level in the crankcase to rise to create problems and/or emission related problems with a large number of vehicles.

 

[blanchard7684]

Good point about the hp fuel pump leaking…

 

[jfoj]

Another thought, how is the vehicles fuel economy?

With a higher percentage of fuel in the oil, the fuel economy will suffer.

This is my hypothesis, if something is wrong with the engine fuel management, the engine thermostat being soft or exhaust flap being stuck, I would assume the fuel economy would be noticeably worse than if there was just raw fuel leaking into the crankcase from the high pressure fuel pump.

If the fuel is working into the oil from the cylinders, fuel economy should be far worse than the fuel just leaking into the crankcase from the high pressure fuel pump.