My 95 pays me to put premium in it plus she smokes a little at 65+ with regular

 

Now that you say something my gauge in the truck says that my temperature is around 120 degrees, and it never goes above 120 degrees, it could be the gauge or the thermostat is stuck open. Next time i run it when i get home i will take the temp with a gauge that i know works.

 

Do you use high mileage oil?

 

Well this may not be applicable because my Blazer isn't 4 wheel drive but I get about 16+ in town and 20+ on the highway. It's a '91 with the 4.3 so it doesn't have the vortec engine which has 200hp, instead it has only 160hp with 230 ft/ lbs torque. These trucks arn't quick accelerators but are steady accelerators, even under load, due to thier torque. I've pulled thousands of pounds with this truck and the acceleration seems to stay the same with or without the load.

 

I just use mobile 1 synthetic oil, and today i am replacing the diffs with mobile 1 synthetic gear oil, and the transfer case with a decent oil. My thermostat is also bad, i checked the engine temp with an external gauge and it also reads 120 degrees F. This could be the cause of some of my problems

 

Yeah if you are only getting to 120 that would cause low mpg. If you put in a new 195 thermostat and do a coolant flush to clear out any gunk.

 

okay this is now progressing from a low mpg to a help me fix my engine =/. I replaced the thermostat this morning, and did a coolant flush, my old coolant was looking very orange but you could still smell the antifreeze, i replaced it with a 50/50 mix of antifreeze and water.

Took it around town, never got much hotter than previously, i checked the temperature with the external thermometer and it read as high as 140 degrees but still not my 190 i am looking for, what else could be wrong?

 

I have a 98 blazer, and I drive about 25,000 miles a year, about 75% of that being highway. I get about 22 mpg during the summer and 18-19 during the winter. I've found that using mid grade gas really helps with performance and gas mileage. Paying a few cents extra is worth it to me. I'm also running Amsoil and have a high grade K&N air filter. Like others on here said, the type of tires you have as well as keeping the air pressure where it should be also makes a difference.

 

my sons 96-4.3 vortec 4x4 16 around town and just dropped to 13. engine was rebuilt last year. 2 ox sensors read lean but that has been that way even before gas mileage drop. anybody got any suggestions

 

You said you have a 2000 Blazer? Your truck came with Dexcool (reddish-orange). Did you flush the block as well as the rad and heater core to get ALL the Dexcool out before you put the green stuff in?