Gears, mpg, could use some wisdom

[turbopbw]

Currently my 96 5.7 auto with 3.08 axle 2wd extended cab averages 15.18 MPG, over last 5,000 miles in mixed driving. The motor could use some new plugs and wires. Tomorrow I'm going to swap the rear axle out for a 3.73. I feel the 3.08 is way too low.

 

[bluex]

That will get the truck moving a lot easier an if you keep your foot out of it your mpg should improve if the engine is in good shape. I knock down a consistent 16 mpg with my Z71 (before the lift/tires anyway) so yours should be over that I would think.

 

[96-1500]

Last tank of gas, 21.1 L/100km or 11.15 MPG. Some of this was loaded mind you. And whilst I don't particularly like spending a $20 bill every time I need to get to town, when the truck is loaded it works considerably better than my previous truck did with the gears I'm running. Not to mention the fact that there was practically zero frame flex and it only squatted the springs a little with around 2'000lbs in the bed. Hardly noticed it behind me really.

Looked at a '92 GMC K2500 6.2L diesel, standard with 3.73s the other day. Low mileage in really good shape. Very seriously considering buying it. Slightly out of my current price range is the only hiccup.

I also started doing a little math recently (insurance, gas etc.) and am thinking for next year, saying to hell with the pickup idea and owning two vehicles. One would be an old beater car. The other? Well, I have a line on a '94 C3500HD with a 14ft flatbed dump and 6.5L standard.

 

[DieselBurner55]

I get 17 out on the highway with my 3.73 empty and about 13in the city.... Also try changing all your fluids to synthetic it bumped my mpgs up over 1.65 on the highway.

 

[bambam78]

I drove 600 miles to and from kings island in ohio, and averaged 17, just a little tid bit from 18s on the highway



i have a 350 jasper engine, with 460le, 3.42 gears and 265 tires, oh and its 4wd, not to bad for a full size 4x4 truck

 

[94Sierra4x4]

My 305 with nv3500, 3.73s.. 6200 lb GVW. has been getting an average 5 km per litre. about 11.8 mpg by my calculations.. town driving and hilly/windy not what you'd think is a highway but is.. driving.. ty roads around here. thats will new plugs, wires, cap, rotor, fuel filter, air filter.. oil, oil filter.. pretty tired motor, bout 265 000 km on it.

 

[96-1500]

Wow, seems like TBIs are a lot worse than Vortecs mileage wise. Throughout the life of my 96 RCLB 1500 (4x4, 4L60E, 5.7 vortec, 3.42s), I averaged about 19. Highway was usually around 20.5 depending on where I was. Absolute worst ever was when I burned 3/4 of a tank running wood around Fredericton all day, busy city traffic fully loaded up with half a cord on, and I got 15.5. Truck had new AC delco plugs, new wires, cap, rotor, air filter, I cleaned the throttle body and injectors, but was a completely stock intake and exhaust. Had around 375k when she calved.

Biggest thing was keep your foot off it. But I can't even touch it with my 3/4 ton. I'll try synthetics, maybe do the rear end fluid as well, I think I'm going to re-think my exhaust also. Might see another mpg or so by the time I'm done.

 

[96-1500]

I should have also mentioned this is an everyday work vehicle and driver. I use it for everything, and often have to put on a couple hundred KMs per day. Not so bad right now, but come spring I'll need it for hauling gear again and an extra couple miles to the gallon, even if it costs me a few hundred bucks to achieve, would be a major difference for a work truck.
I was going to park it and put an old Grand Prix I've got back on the road but I don't think I'm going to bother, it needs a lot and just hasn't been a good car. Sometimes you have something that no matter what you go over and replace, it just isn't a reliable vehicle. That Pontiac is one of them. It's going to be somebody else's problem soon I think. Plus it would only be a couple months before I'd need the truck again, so I don't think it would be cost-efficient to license, inspect and insure another vehicle.