Gas milage

2000 GMC · September 23, 2001

I have 14,400 miles on my 2000 GMC. It's a Z-71, ext cab, 5.3 V-8. I bought the truck used about 3 months ago and have kept track of milage since then. I switched to Moble 1 about 400 miles ago and noticed that my gas milage as gone down, from about 13.4 to 14.7 in the city to this last fill up down to 12.6mpg. I have bought gas at a different place these last 2 fill ups. Could it be the gas or should I have it checked out by the dealer since it's still under warranty? My driving has stayed the same.

Thanks ???

chevy4x4trucks · September 23, 2001

I don't know, I bought my truck new and yet to see mpg go over 13. I have a 4.8 and I've run mobil one synthetic since about 2,000 miles (15,000 on the truck now).

DigUout · September 23, 2001

I can't imagine that it's due to the Mobil 1, that your mileage has decreased. I'm also not sure what a dealer would be able to do for you, other than give you some BS or blow you off. I know you said you're driving has stayed the same, but maybe there was an instance or two where you punched it at a light or opened it up on a straight away?

With 14K+, maybe adding a little fuel injection cleaner, more air in the tires? It just seems like a small decrease that could be the result of many little things; left it idling, ran the A/C more, had a small load in the bed one day, etc. If you're getting near 13MPG, that seems about average. I wouldn't get to worried about it yet -

TurboShane · September 23, 2001

What kind of gas mileage is average for the 5.3? I get between 16.5 and 17 mpg city and highway driving.

2000 GMC · September 24, 2001

I'm thinking it was the fuel. We took a drive this today and were up in the mountains. When we got home I topped it off just for the heck of it and came up with 18.33 mpg.

TahoeJeff · September 30, 2001

I am real happy with my mileage, on my 2WD 2001 Tahoe 5.3 with 3.42 rear. I just did a check over 450 miles and had a average of 18.33 this is mostly in traffic moving with some stops at 45 to 55, front AC on almost always, rear AC on sometimes. I have 4000 miles on it now and it just keeps getting better and better! Initially, I was getting about 14 to 16 on the same roads.

y2kz71 · September 30, 2001

I get 16.7mpg in my truck as a combined city/highway 50:50. My truck is a 2000 extcab 1500 Z71 autotrac 4.10 gears with a Rancho lift and 33's. I am very pleased with the mileage escpecially since I have 48k miles on the truck. I used to have a 1997 Ford F150 extcab 4x4 same gears and even if I drove like an eighty year old woman I could never get more than 12.4mpg combined, that sucked. Chevy has more power and better gas mileage.

alsz71 · September 30, 2001

Humm ..... I drive 100 kms/62 miles a day about 70% highway and obey most of the speed limits , just filled up and came up with 21.3 mpg. I don't think its downhill both ways so whats up ?:notice:

Ps 5.3L with 23000kms/14285miles

Ranger Dave · September 30, 2001

Dump some of GM Cleens down the throat of the throttle body. It will clean out the carbon. My friend had an increase of 3mpg on his 99 Z71 5.3.

Stepside Z · October 1, 2001

On my last trip to Maine I got 19.7 mpg running as fast as 87 mph with the AC running. That was befor I change to the BFGs.

mjsmith1223 · October 1, 2001

Just drove out to Lancaster, PA and back this weekend. 1400 miles of driving - ugh. Anyway, we got just a shade over 18 mpg. Around town we get about 15.5 mpg. We have the 5.3 and it has about 2000 miles on it now. Still has the original oil in it, but I'll be changing it out this week.

Mike

Grand Haven, MI

dougs z71 · October 1, 2001

Your mileage seems about right. Try driving with the tailgate down (esp. on the highway) or get a bed cover. Also a K&N filter is definately worth the $50, you'll make your $50 back with the gas $ you'll save.

jaslo · October 4, 2001

why do you think a k&n filter is worth $50. you think it makes that big of a difference.

Stepside Z · October 4, 2001

I have noticed that the engine revs better above 2200 rpm. Overall you get better performance and about .5 mpg gain.

bscottb · October 4, 2001

I'm getting 13.5 city and 17.9 highway with 23,000 miles so far. I haven't done any engine mods at all. I'm happy with these numbers. They are better than any other truck I have owned.