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Posted (edited)

Simple. Pull a oil sample and have it tested to confirm fuel dilution. Don't rely on conjectures, "sniff tests", and other shade tree stuff. If you are going to try and get the dealer to do something, having a recent used oil sample test result in hand goes a long, long way to supporting your argument. You can get UOA kits and testing done for $25 or less from dozens of testing labs and they can have you the results in a week of sending in the sample.

Edited by Cowpie
Posted

This is a normal occurrence with direct injection engines

Posted

Diesels add diesel fuel on an exhaust stroke fueling the DPF sytem to heat up to 1400 or higher....different system! Engine cycles egr gas and soot into combustion cylinder to treat NOX gas, this accumulates in oil changing oil quality, diesels are not gas engines.

Gas engines don't do this, just a simple egr gas only.

 

I was just saying a similar problem I know of. I know they are different motors.

Posted

 

I was just saying a similar problem I know of. I know they are different motors.

Definitely different, but like you said, the cause of the problem is likely the same. Injectors leaking with the engine off.

 

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Posted (edited)

Diesels add diesel fuel on an exhaust stroke fueling the DPF sytem to heat up to 1400 or higher....different system! Engine cycles egr gas and soot into combustion cylinder to treat NOX gas, this accumulates in oil changing oil quality, diesels are not gas engines.

Gas engines don't do this, just a simple egr gas only.

 

 

Clearly, diesel or gas, fuel dilution is a product of improperly set injector timing, leaking injectors, poor piston rings, etc. Excessive idling can cause fuel dilution and excessive short trip, incomplete engine oil warmup will amplify fuel dilution issues by not allowing oil to come up to full operating temperature which is such that fuel that has gotten into the oil will vaporize off and go thru the PCV line back to the intake.

 

Engine up at operating temp does not mean that oil has reached operating temperature. There is a lag, with oil temp coming up slower than coolant temp. This is why operating the engine at normal temps for longer than a short trip is critical to get the oil up to temp also.

Edited by Cowpie
Posted

"This is a normal occurrence with direct injection engines"

 

Yes and no. Based on the used oil analyses I have seen, Direct Injection engines do tend to exhibit more fuel dilution than their non-DI counterparts, but typically does not consist of more than 1% of the oil volume unless there is a mechanical defect (such as a leaking injector as some have suggested).

 

Seeing the oil quantity creep up as much as the original poster's does is not normal. Recommend an oil analysis to see what the % of fuel dilution.

  • 2 years later...
  • 6 months later...
Posted

I also own a 2016 Silverado Z71 that had had an issue with increased oil level, fuel smell in the oil, decreased fuel mileage, and a heavy raw fuel smell on start up. As others have noted, if it doesn't throw a code, the problem doesn't exist. (IMO: This is the difference between a mechanic and a technician.) I have asked my dealer to pull a fuel dilution oil sample, but they still won't and tell me I need to get it done myself. They've stalled this issue to the point that the bumper to bumper warranty is now expired and I've gotten GM Customer Service involved. 

So far, the result is the same. "We can't find anything because it's not giving us a code!"

My truck now has 34K on it and this issue has been present for about 20K and I've even been accused of adding extra oil.

I know it's a leaking injector or two. Rough, noisy start ups, rough idle cold or warm, and a drop of about 6 to 10 mpg over all.

If others suffer from this same problem, I'd like to hear from you, problem solved or not. It's past being old and into the realm of total stupidity. This should be documented to GM and addressed. 

Posted

You've been running your truck with fuel in the oil for 20K miles?  That's a huge mistake, as fuel kills the oils ability to lubricate...

 

IMHO, you need to pony up for the oil test ASAP, and get the problem fixed, as your engine is getting more and more damaged from this every day...

Posted

The issue isn't a consistent problem and I'm not dumb enough to drive it 20K with diluted oil. It's spent quite a bit of time at the dealership, (being largely ignored), and I've finally told them I'll drive the S.O.B. until it blows up. Hopefully, Customer Service is getting Technical involved and we'll have a solution. If not, I'll request they buy it back. 

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