98 Chevy 1500, gas mileage????

Jsledder · January 13, 2003

I've got a 98 Chevy 1500, 4 door conversion, 350, I have yet to get over 13mpg with the thing and I've been driving it real decent. Pulled a 2 place snowmobile trailer with 2 sleds and got 7-8mpg. Had a 94 Suburban and got 17 on a regular basis.

What gives??????? Everyone I've talked to said they average 16-17 on the highway.

k1500chevy97 · January 13, 2003

That does sound kinda low . The mileage for the 350 from that year should be up around 17

When is the last time you had a good tune up on the 98 ??

Jsledder · January 14, 2003

I've only had it about a month, it has 70k on it and so far all I've done is changed the fuel filter.

I'm going to put plugs in it and get an aftermarket air filter also.

Went on a 500 mile trip this weekend and averaged 11mpg and had the cruise set at 65-70 the whole time. Saturday was spent driving around the city though so that brought it down, but the way home was a good 275 mile trip and I got 12 with no wind and 65mph, straight/flat roads also.

For this kind of mileage I just as well got the 454!!!!

CanadianZ71 · January 18, 2003

My 1997 1500 with the 350 and 180,000kms gets around 14-15 mpg (imperial) in the city and i've seen up to 20 mpg on the highway pulling a small tent trailer. Not sure what these numbers equal to in US gallons but your milage seems a little low to me. Try plugs, they made a little difference for me. I have also heard that if your milage is bad O2 sensors could be the culprite.

Jsledder · January 20, 2003

And I spose the only way to tell about the 02 sensor it to take it to a high priced mechanic and have him hook up his high priced monitor to tell me that right???

CanadianZ71 · January 20, 2003

I've seen it on some internet site somewhere where there is an explaination on how to test O2 sensors yourself. Sorry I don't remember what site it was but it was beyond my backyard mechanic capabilities. If your handy and know how to use a multimeter I think thats all it takes. Sorry I can't be of more help, maybe someone else here has a better idea than me? A friend of mine started getting bad milage and just changed his on his 1996 and he noticed a difference right away. This is a little pricey too as our trucks have four 02 sensors and at around 60 bucks a pop it adds up. Upside is they are easy to change yourself.

CanadianZ71 · January 20, 2003

Here, I found on link that might help. If not try doing your own search under "testing O2 sensors". Hope this helps.

http://www.gracieland.org/cars/techtalk/O2_1.html#bad

Jsledder · January 22, 2003

Thanks for replying and helping out Canadian, I'll check out the site and see if I can learn anything.

I changed from Super Unleaded (10% ethanol) to regular unleaded this weekend and noticed a 3-4mpg increase, which seems odd to me.

bowtie_pasta · January 23, 2003

From what I understand unless your vehicle's engine is high performance or the manufacturer specifically calls for high octane fuel you should just run regular unleaded. Another reason to run a higher octane would be if you are experiencing knocking or pinging.

If you are unsure check your owners manual.

PharmZ71 · January 23, 2003

My '97 350 gets about 15-16 mpg with about 60/40 City/Hwy.

I do have a throttle body spacer. Dunno if that helps or not..it was on there when I bought it, but the mfg claims an extra 1-2 mpgs. Who knows.

Race18 · June 9, 2003

I get anywhere from 17.3 to 18.4 mpg that is driving 89 miles each way to work with about 50% highway and 50% city in Charlotte NC. But I have a 342 gear and then put 285's on. So my gear is about 308 with larger tires. I can't complain but would always like more.

satch · June 24, 2003

i get 20 to 21 mpg if i'm empty and keep the speed at 60 mph on the interstate.....if i speed up to 70 to 75 mph the milage drops to 17 to 18 mpg....and about a month ago i had the chance to pull a tandem axle u-haul loaded pretty heavy on the interstate at 70 to 75 mph and the milage went down to 11 and 12 mpg.....the towing was between phoenix and key west, 2500 miles using middle grade fuel....normally i use the lower grade but it was pinging a little so i went to the next higher grade while i was towing...

bigtruck21 · June 26, 2003

octaine rating is how stable gas is. higher octaine is needed for higher compression engines or higher heat. If your engine is tuned for 87, when you run 93 it will blow up too late...when the piston is already heading down the cylinder instead of directly on top. You lose push of the piston, which means less power, which means giving it more gas and that is lower gas mileage.