Oil Consumption and Gas Mileage

coronetrt101 · December 27, 2005

I have a 2003 Silverado with the 8.1 and allison trans & 4.10 rear...plus all the bells and whistles... I have seen many post about gas mileage and also oil consumption but nothing comparing the two....

My oil consumption was a bit heavy with more than a quart every 1000 miles so I decided to have Chevy run a consumption test. Since its under warranty and after hearing about the piston slop issue and also having a buddy that had his engine meltdown...

Anyways, my gas mileage has been really crappy even for the 8.1 at 6 mpg city... I really dont do highway... but the strangest thing happened... Just as I started getting quite a bit better mileage about 8.5 city and my oil consumption went thru the roof... in a little over 1000 miles I used 2 1/2 qts.....

HAS ANYONE HAD ANY EXPERIENCE LIKE THIS???? Also DOES ANYONES 8.1 IDLE REALLY LOUD... my truck almost sounds like a diesel at idle and its not.. It was the sound that made me bring in the truck for the Oil Consumption test in the beginning....

All of this has me really concerned and I have made an appt at the dealer for their Heavy Line.... I am kinda nervous that they will make matters worse.... Any suggestions would be appreciated... I am concerned that I will be towing my 5th wheel and get stranded when the engine dies....

dewfpo · December 27, 2005

Coronetrt101,

It sounds like we have about the same truck except mine's a '05. My truck has 4,600 miles and it does not idle loudly (except for a belt chirp), city mileage is acceptable. I've averaged 12.8 mpg over those 4,600 miles with mostly city and rural driving and very little highway driving. My idle is rough to very rough all the time, but no smoke, decent mileage and I'm not burning excessive oil (to my knowledge). I changed it at 3,700 miles and have not checked it since (I should do that). I live in the mountians and whenever I use the truck I rarely wind up parking in a flat spot. I just have to remember to check it.

DEWFPO

Shaners · December 28, 2005

If you live in a colder climate, and run alot of short trips where the motor never fully warms up, then your milage will be worse than most.

On my old truck ('01 2500HD 6.0L), I once had a tank of fuel that only netted about 6.5 mpg's. I attributed it to winter blended fuels and lots of short trips (less than 5 miles), plus seasonal Pennsylvania temps.

2.5 qts in 1000 miles is excessive oil use. GM says 1 qt/1000 miles is OK. I still think it's excessive, but that's me.

coronetrt101 · December 28, 2005

Shaners,

You are exactly right about those short hops... I was only getting 5.8 - 6.2 mpg for awhile when I stopped driving it any distance...

Buy I just did a 700 mile trip with a 10k lbs 5th wheel camper and thats where I eat up the oil. I bet 2 1/2 qts surprised them, it sure blew me away.

The service rep told me that they will have to take a further look. I am concerned what is in store for the engine. Does any one have an idea of what the dealer might do on their HEAVY LINE???