How often to replace spark plugs?

[radioouman]

I replace my Iridium plugs every 100,000 miles.

 

[LTC8K6]

copper plugs? I imagine it is relatively easy.

Yep. Champion 570's. 2008 Grand Cherokee. Possibly only the back 4 will be a little difficult.

I'm glad I don't have that new 4.7L V8. It has 2 different kinds of plugs.

4.7 V8 (2008-2010)
Mopar p/n 5149050AB (Bosch Nickel Yttrium) (intake side)
(.040 gap, 8 plugs, tighten to 20 ft. lbs.)

Mopar p/n 5149888AA (Bosch Iridium) (exhaust side)
(.050 gap, 8 plugs, tighten to 20 ft. lbs.)

CAUTION: This engine uses TWO DIFFERENT types of spark plugs. A total of 16 plugs are used. The plugs are mounted in two rows (banks). The upper row is used on the intake valve side of the cylinder head. The lower row is used on the exhaust valve side of the cylinder head. The upper row uses Bosch Nickel Yttrium plugs. The lower row uses Bosch Iridium plugs. DO NOT INTERCHANGE THESE PLUGS.

 

[sdifox]

Yep. Champion 570's. 2008 Grand Cherokee. Possibly only the back 4 will be a little difficult.

I'm glad I don't have that new 4.7L V8. It has 2 different kinds of plugs.

what on earth would possess anyone to make that decision? Even if you don't need irridiums on the intake side, why not just use iridium to avoid issues?

 

[LTC8K6]

what on earth would possess anyone to make that decision? Even if you don't need irridiums on the intake side, why not just use iridium to avoid issues?

You got me...it's even a little weirder.

The top row are 30K interval. The bottom row 102K interval.

NOTE: ** Vehicles built with the 4.7L engine are
equipped with sixteen spark plugs, one set is located on
the top of the engine under the coils and the second set is
located on the side of the engine.
The spark plugs located under the coils are a standard
plug and must be changed every 30,000 miles (50 000 km)
The spark plugs located on the side of the engine are a
premium plug and must be changed every 102,000 miles
(170 000 km).

 

[sdifox]

You got me...it's even a little weirder.

The top row are 30K interval. The bottom row 102K interval.

Morons the lot. Just demand iridium on all of them, end of story. The time spent making sure you grabbed the right plug is going to cost a lot more than just using the iridiums.