I've concluded that my car must have been running rich (new O2 sensor produces significant improvement in MPG).

I understand that excess fuel in the combustion chamber can "wash" oil off of the cylinder walls-- very bad.

But can this excess fuel in the combustion chamber cause a significant increase in oil consumption? I'm just wondering if I wont be consuming so much oil anymore. Did i fix at least part of my consumption problem?

Or I am just "wishful thinking?" Blowby is mostly unrelated to running rich. And the better air fuel mixture will not really help my oil consumption?

 

i don't see it making any difference. how old is the engine? is the thing coated in old or is it smoking?

 

There should be little difference. Blow-by is going to be dictated more along the lines of the piston ring clearance and the PCV system.

 

How many miles, consider switching to synthetic? (unless you already have)

what viscosity oil do you use, 5w30 or 10w30?

 

Thanks for the responses.

My civic has 198,000 miles on it. It's been a bit of an oil burner since i purchased it 7 years ago. At first it would only burn on long highway trips during hot days. But now it's gotten a bit worse. I use thicker high mileage oil to manage it.

Actually I've already posted on this topic extensively. And i've already looked at the pcv valve, parking over a piece of cardboard to spot leaks, bandaids, etc.

It's just that the new O2 sensor made such a dramatic difference i was hoping it would improve consumption -- wishful thinking.


[On a side note, fresh oil doesn't get burned as quickly. I attribute that to unburnt fuel mixing with the oil. Thus the diluted oil loses it's 'sealing' properties.

 

I would say that the only thing that will make it better is to put in some new piston rings. as someone above said, its a ring clearance issue first and foremost. another failure point on our engines is the valve guide seals. if either of those are an issue, you will burn oil.

the next question is whether or not it is worth rebuilding, or should you just swap it.