I see a lot of people saying to use a 3928 spark plug I believe it was. I have a "97 Dak sport extended cab 5.2, auto 4x4. Why is this beneficial? I am only getting about 13-14 mpg out of my truck and tuned it up less than 12,000 miles ago, I used Bosch +4 plugs. I see a lot of people don't like those. Truck seems to run well. 3928's are what brand and type, copper, platinum, etc. I was thinking of installing some of the stock Champion plugs, don't remember the number, to see if it would help the gas mileage. I have Seafoamed it and used Techtron in it also. I only put about 5,000 miles a year on the truck. Mostly winter, it has 97,000 miles on it. Looking for a good explanation on how the 3928 plugs work better. Thanks.

 

Maybe it was 3928 plugs?

 

I believe most on here are using Autolite 3923's and 3924's with great results. For some reason the magnum motors prefer them as opposed to most other plugs and heat ranges.

 

3923, thanks, was trying to remember the plug number.

 

Mine ran good with the 24's but reading the plugs gave me 6 running slightly cool and two running slightle warm. I switched to the 23's to get a little more heat on the six and plan on reading 1&2 at 1K miles for too hot or blistering porcelyns. I dont think there is any diff, but it seems to start cold better, however the plugs I replaced looked like they crossed the Deleware with George Washington! Maby in a week or two I can afford wires and a new cap.

 

Im runnin 3923's in my truck I've had them in for about 8,000 miles and so far they are fine im still only seein about 12-14mpg tho I think thats normal for these trucks

 

I decided to try the stock Champions, installed them this evening. Had Bosch +2's in the truck. Seemed to be running OK on the Bosch plugs, but I will see what happens with the Champions. May go with the Autolite 3923's later. Are the Autolites copper, platinum, or what?

Thanks everyone for the input.

 

Copper

 

3923's here

 

So with mine carring a couple hundred lb of tools and equipment and 130+ K on the 94 5.2 I should be happy with 16 to 18. Its a heck of a lot better than the Ford 5.4 that threw a plug cause Sons fantastic mechanic didnt torque e., oh forgot Ford gets 9 to 12, but it weighs in just under 4 ton.