I have a 99 Ford V-10 that I pull a 5th wheel with. I believe the owners manual directs changing plugs at either 50,000 or 60,000 miles under heavy duty service use, instead of 100,000 miles.
I talked to my mechanic about this and he could not think of any reason why they would suggest more frequent change under heavy service unless one was overheating the engine. I had him pull one plug to check it aroung 70,000 and he said it looked fine.
Does anyone have any knowledge about the pros and cons of this recommendation. I presently have 82,000 on the truck and it runs fine and gets decent mileage.
Thanks, LIKENIT

 

Under any conditions I wouldnt go the 100,000 miles. The early mod motors have had problems with blowing out plugs. I went to 90,000 miles before changing mine (F250). I still need to do the X because its at 95,000 now.

 

40-60,000 miles is the max I would go on any enginebefore plug change. The main issue is the torque on the plugs that were factory installed. The plugs in the aluminum head have been known to loosen or worse yet, rust in the holes.

 

Every plug wears each time it fires.

So, the higher revving the motor, over so many miles, the more the plugs wear.

I'd also suspect that the denser the air/fuel mix, the more they wear also. More O2 to oxidize the electrodes.

So, work the engine, the plugs wear out faster. Plain and simple

 

changed original plugs @ 75000 and even tho the truck seemed to run fine the gap had widened to .64. with new autolite app103's gapped to .54 the truck ran much better