At 68,000 Miles, Something Changed

[N900WM]

So this summer my truck turned 68,000 miles whilst on a trip towing a trailer.

 

On this trip, I had to ad 2 quarts of oil. I discounted it. I paid no attention to mileage as it's bad...always bad and it should be.

 

Now that I'm home and driving it around like usual, I have noted that my fuel milege, which was ALWAYS 9.7mpg has gone up to 11.5 and sometimes 12mpg. In addition, what used to be no requirement to ad oil between oil changes and a quart every 3,000 miles every once in a great while, has now gone to a guarenteed two quarts every 3,000 miles.

 

I can understand the oil usage to a degree. But the fuel mileage has me baffled. Driving style has not change. Mods to the truck have not changed.

 

Any ideas?

[naylor]

That motor is notorious for using oil. However, two quarts is a lot between regular oil changes.

[ChevyMan02]

From what I've read on here it is within GM specifications to burn 1 quart of oil for every 100 gallons of fuel. Not sure on the change in fuel mileage. Did your air filter fall off?

[JJinMT]

I also have experienced the 2 quarts used in between oil changes but no increase in gas mileage for my 01 Sierra 2500HD SLT CC SB 8.1 Alli with 49K on it. Have ordered K&N Filter Kit. Am considering other Mods for performance and mileage. We pull two trailers with our truck when we hit the road. Will be considering some kind of tuneup. Will be also making the attempt at learning to program the ECM. Have never gone there. Quit working on my vehicles when they came out with the ECMs on everything. Anyone with any ideas for improvements on my rig would be appreciated.

[evilone93]

I was told that the intake mounting seals on the 8.1 are notorius for leaking, but where does the oil go? It's not on the ground and its not in the coolant or exhaust. I guess I'm lucky I only lose a quart every 3,000. This week I finally came to the conclusion that I bought a POS and need to figure out how to get rid of it!

[N900WM]

I would not classify my truck as a POS. Yes, it now uses 2 quarts of oil. Something went wacky with fuel milage but to my benefit.

I'm not complaining.

I work it hard. This has been the best most reliable truck I have ever owned. And I have has my share of both GM and Ford JUNK.

[BigJayDogg3]

You want to get rid of it you can give it to me.

[polarisboy]

I believe there is a service bulletin for oil consumption caused by the PCV valve. I think they have an updated one with different valving inside. Might want to check into that.

 

Not sure about the mileage thing, it's good though!