I have a 98 Ram 1500 2wd pickup and i was wondering what is the best plug at first i was using Bosch and then i switch to champion and now i am noticing my mileage going down so what is the best plug to use.

 

Check the Spark Plug thread in the FAQ section. I used AC Delco plugs..... they work just fine. Don't bother with the expensive platinum/Iridium/Unobtanium plugs. Doesn't help, and in some cases, can actually run WORSE in our trucks.

 

The one that came from the factory and what the engine was designed for which is champion gapped to factory spec. You got other issues then the plugs. Heck going from summer to winter fuel blend will decrease mpg.

 

Yeah but it has been going down as soon as it was switched. And I traded the plugs out in august and was going down then i was getting about 20 with the Bosch supper plus and with the champion i am getting about 16 17mpg. So that is why i thought it was the plugs and there are gaped to the right spec. I will be switching the cap with one that is brass and i think that the one in the truck is original. I am just trying to get to the best fuel economy possible. so any idea where else to look would be good if its not the plug.

 

Check the plenum thread stickied at the top of this forum, even the sixes suffered from that particular gremlin.

O2 sensor might be something else to look at. They are usually a victim of a blown plenum in any event, as are the cat converters.