Dodge Durango Forum II Archive

Re: spark plug question

5224, with the "extended power tip," is the stock replacement. The 3924 is the corresponding version with the normal tip (protrudes less into the chamber), and the 3923 is one heat range colder - dissipates heat faster. This plug has been dyno proven to give 4 HP more at the rear wheels and can alleviate pinging problems under load. If you do a lot of stop & go driving, or drive short distances where the engine doesn't fully get up to temperature, the 3923s may foul - in this case, go with the 3924s.

Personally, I would take my business to a store that sells me what I ask for. NAPA handed the 3923s over, no questions asked - but I asked for them specifically, rather than asking what plugs would go in my truck.

Fri Jun 29