GM 5.3 gas mileage

zr2blz · Aug 2, 2011

my 2000 yukon, with 5.3, and I believe 3.73 rear and auto trans gets about 14mpg, and only uses about 2qts of engine oil per 3000 miles... since new.. and gm says that's normal

soundguy, my brother-in-law also had 2000 yukon xt (big one) and it used lots of oil. After many different GMC dealers, one mech knew the problem. He replaced the PCV and it stopped using oil. The hole size was wrong (can't remember, but i think he said it was too small).

Soundguy · Aug 2, 2011

mines the big yukon as well. will look into that.

did he go to a non stock/oem pcv.. or simply the one supplied was damaged?

soundguy

Diamondpilot · Aug 2, 2011

Soundguy said:
mines the big yukon as well. will look into that.

did he go to a non stock/oem pcv.. or simply the one supplied was damaged?

soundguy

GM's have been picky on the PCV valve since the 4.3L engine was introduced. I tried different ones on both my Saturns, maybe 10 total from GM, Auto Zone, Napa, Car Quest, On-Line, ect and none made any difference on mine, they still drank a QT of oil every 800 miles when using 10W30 and a QT every 600 miles when using the recommended 5W30.

I really just think its a GM thing. 1/2 the guys I know use no oil in there GM trucks and cars but the other 1/2, especially the 8.1 and 5.3 motors use from 1 QT to 3 QTS between oil changes.

Chris

lostcause · Aug 2, 2011

i've only owned one 5.3 - a 2001 yukon. i i used to pull close to 18 mpg with that before i sold it (dec 2006), but i would guess that would be more like 16mpg with the current fuel based on my experience with the rest of my vehicles.

my current truck is an 06 gm 2500 4x4 crew with the 6.0 and 4.10 gears. i've been keeping track since early this summer and i've averaged 14.2 mpg over 2000 miles. that is mostly 45-55 mph driving with about 25-35% interstate and city driving mixed in. most of the driving has been hauling light loads in the body too (~500lb of tools, people, or similar). the last truck was a near identical 2000 crew (previous body style, 5.7, 4.10) and i got about 1mpg less economy than immediately after i bought the 06, back before ethanol.

back in the 90's i knew lots of people with 5.0 and 5.7 gm engines in 1/2 ton 4x4 trucks. to the best of my knowledge, the 5.0 crowd ever got the economy that the 5.7 crowd did. i'm not an expert on the engineering of those engines, but i wonder if all the added emissions and creature comforts were taking a lot of what that smaller engine had to give, so it had to work harder to get the job done, hence the sub-par fuel economy.

WilliamBos · Aug 2, 2011

I know they are saddled with 'Torque Management' You can have your PCM tuned the way you want, like for better mileage, but leave the tow/haul alone, as it is programmed to protect the transmission.

I am considering a custom tune, as I am well off of warranty.

Soundguy · Aug 2, 2011

Diamondpilot said:
GM's have been picky on the PCV valve since the 4.3L engine was introduced. I tried different ones on both my Saturns, maybe 10 total from GM, Auto Zone, Napa, Car Quest, On-Line, ect and none made any difference on mine, they still drank a QT of oil every 800 miles when using 10W30 and a QT every 600 miles when using the recommended 5W30.

I really just think its a GM thing. 1/2 the guys I know use no oil in there GM trucks and cars but the other 1/2, especially the 8.1 and 5.3 motors use from 1 QT to 3 QTS between oil changes.

Chris

yep.. is close to 3qts on teh 5w stuff.. so I've been putting 10w in there so it don't go low between me getting my hands on it to check it

bdeboer · Aug 3, 2011

I owned a '99 5.3, '02 6.0, and still own a '05 5.3L and haven't had any oil consumption issues. The mileage on the 99 1500 5.3L ec/sb 4x4 was always around 15/17 unless towing. The '02 K2500 Suburban 6.0L/3.73 was about 12/14 with a custom tune on it. '05 regular cab 4x4 work truck with 5.3/3.42 gears was more like 16/19 when new. Seems to be alot lower now with the ethanol gas, mud tires and a work cap that sticks above the cab. Does alot of less than 2 mile trips with tractor or firewood trailer in tow.

daveinnh · Aug 3, 2011

deerefan:

We have a 2009 GMC 1500 crew cab with same motor & rear end. Trip from NH to Buffalo was 18.5 mpg but only about 15 locally (never got to 5th & 6th gears).

Two thoughts: my mileage was low iniatially ; ensure your air filter is clean.

zr2blz · Aug 10, 2011

Soundguy said:
mines the big yukon as well. will look into that.

did he go to a non stock/oem pcv.. or simply the one supplied was damaged?

soundguy

I think the mr goodwrench put in a '99 PCV and oil problem was fixed. He sells all his cars before he puts 75k on them so its was sold in 03 or 04. He did drive it to Alaska while it was using lots of oil.