actually some S-blazer dont do as bad on fuel as you'd think. my wife drives a '97 , its a 4wd 4.3 , 4speed auto, 3.42 gears, gets around 16-17 in town, has gotton nearly 23 highway. and it has 185,000 miles on it, uses about a qt of oil every 4,000 miles. im running 225/70-15 tires on it, tuned it up just a year ago and compression was a pretty even 180 on all 6. by comparason my '93 ranger with a 4.0, 3.73's, 5 speed manual gets about 15-16 in town and the best i ever got with it was 19.5 highway. and the ranger weighs a thousand pounds less. its not logical, but it is true. some 4.3's do better than others, dad's current S-blazer is a '05 and only gets 20 at best, 15 most of the time.

 

My S15 would get 15 city, 18 or so freeway if I kept to 65-70 tops. It was a 4wd with 3.42 gears. My Typhoon, on the other hand, got 14 no matter what on 93 octane. 4.3 turbo with 3.42's and full time AWD.

 

My '94 Jimmy on stock size tires got 19-20 MPG mostly highway on a regular basis, decent running shape. 17MPG or so around town. Needed a new CPI spider too. I've personally been in one that did 23MPG on a 100% highway trip. It was an '01, 4.3, 4 Door, 4x4 on stock size tires.

 

A old neighbor had a 4.3 Blazer, got barely 15 on the highway, our 4.0 Explorer was pulling down 23-24.5 on the highway consistently.
The 4.3 is a good motor, there is no doubt..........but mpg wise, it leaves some to be desired.

 

HAD A s10 blazer in the winter in 4x got 10 and in the summer got 13 mpg. 1996 blazer s10 4 door. 4.3