E85 or regular gas?

[swathdiver]

The admittedly very small amount of fuel that sneaks past the piston rings does slowly dilute motor oil.

What happens to the oil after it gets hot and the fuel evaporates? Is the oil no longer diluted?

I've never paid attention to the numbers of my oil analysis, it appears that the oil starts out at 11.8/67 and when tested at the end of the oil change is about 10/59. I don't know if that's good or not, but the motor doesn't rattle and got better mileage and the oil usage basically stopped after switching over to ACDelco and Quaker State from M1.

My 5.3 will hit 212K in a few days, still no catch can on it or any of my trucks. She's completely stock save for the BlackBear tune and Magnaflow cats and y-pipe and makes an average of 325 rear wheel horsepower through the traps in the 1/4 mile.

 

[Marky Dissod]

What happens to the oil after it gets hot and the fuel evaporates? Is the oil no longer diluted?

Ask your motor oil analyst. Once fuel gets into motor oil, it doesn't evaporate as easily as it would out in the open.

I've never paid attention to the numbers of my oil analysis, it appears that the oil starts out at 11.8/67 and when tested at the end of the oil change is about 10/59.

I'll go so far as to say that I don't know what those numbers mean. What units do those numbers measure?
It's as if I said I'm '3.8333'.

... oil usage basically stopped after switching over to ACDelco and Quaker State from M1.

Most people don't realize that the OTHER thing you just said, is 'I change my oil often enough'.
If anyone extends their oil change interval far enough, even with the 'best' motor oil, bet it'll use up some of it.
Partially because normal engine movements do physically wear down motor oil,
partially because motor oil gets diluted by fuel over time.
Obviously the krappyer the motor oil, the more susceptible it is to oil consumption.

 

[swathdiver]

Ask your motor oil analyst. Once fuel gets into motor oil, it doesn't evaporate as easily as it would out in the open.I'll go so far as to say that I don't know what those numbers mean. What units do those numbers measure?
It's as if I said I'm '3.8333'.Most people don't realize that the OTHER thing you just said, is 'I change my oil often enough'.
If anyone extends their oil change interval far enough, even with the 'best' motor oil, bet it'll use up some of it.
Partially because normal engine movements do physically wear down motor oil,
partially because motor oil gets diluted by fuel over time.
Obviously the krappyer the motor oil, the more susceptible it is to oil consumption.

Well, I was asking you because you are saying that fuel is diluting our oil and I am trying to understand how.

I think those numbers correspond to ASTM D445 viscosity numbers.

 

[Marky Dissod]

Well, I was asking you because you are saying that fuel is diluting our oil and I am trying to understand how.

Not all the injected fuel is burned. Before some of it escapes during the exhaust pulse,
some of it sneaks past the rings during the compression and power strokes.
I'm no Lake Speed Jr. Between me and him, there are plenty qualified to explain the details better than I.

 

[dwinters14]

This went off topic, but to answer the E85 vs Regular Gas... E85 hands down. I have used it now for over 3 years consecutively and on a GMT800 and GMT900. The trucks are way peppier, smoother, and smell better. I haven't lost a significant amount of MPG in the process either. I bought my current truck with an average of 14mpg's from the previous owner and it's dropped to 13.5mpg. I almost exclusively drive on the street in stop and go traffic.

Regular gas here is $4.19 + and E85 for me is $2.59. 38% price difference and slightly worse fuel economy but everything else as an advantage? No brainer.

 

[Fless]

Oil diluted with fuel can affect fuel trims and the fuel vapors can cause the computer to take away metered gas (so, negative fuel trims). Something to watch for after having a rich condition for a while. Fuel trims can tell a lot about what's going on inside...

 

[Marky Dissod]

Regular gas here is $4.19 + and E85 for me is $2.59.
38% price difference and slightly worse fuel economy but everything else as an advantage? No brainer.

In your case the price maths work.

 

[Marky Dissod]

Oil diluted with fuel can affect fuel trims and the fuel vapors can cause the computer to take away metered gas (so, negative fuel trims).
Something to watch for after having a rich condition for a while. Fuel trims can tell a lot about what's going on inside ...

Yes, this is absolutely true, but I was speaking on a much smaller scale.
Fuel vapor that makes it past the piston rings into the crankcase, hopefully,
get recuperated by the PCV system, although this is the other source of oil burning as well.
Catch can only helps by separating oil vapors from fuel vapors.

 

[Fless]

In your case the price maths work.

The math works even better if you're comparing mid-grade or premium, for the performance difference.

 

[Marky Dissod]

Think it depends on local corn prices. For me, e85 is too expensive in NYC, but the price is right in Long Island.