Pack of 4 Autolite XP3924-4PK Iridium XP Spark Plugs Review

Changing spark plugs on an old Corvette is difficult. Why should I use anything else? They last at least 100,000 miles. Also use Iridium plugs on my Harley.

My purchase was as expected The reason I rated average mileage and durability is because my application is for a racing engine. I haven't had time to prove it honestly, but I'm sure they will prove the point

Replaced a set of NGK spark plugs on a 1996 Miata with these Autolite Iridium spark plugs. Noticeable improvement in starting speed and engine smoothness. Changed exhaust sound, slightly more hum and clearer noise when shifting gears (full exhaust). All in all these are great spark plugs and they fit my Mazda perfectly.

I used to buy the same Autolite iridium spark plugs from O'Reilly's Auto Parts. I bought them from Revain as they were half the price, but when I got them it was more than obvious that they weren't made on the same equipment as the ones I bought from O'Reilly. Obviously, these were Chinese fakes and not of the same quality as real automatic ignition spark plugs. Save money and time and buy genuine spark plugs from your local auto parts store. You never know what you might get from Revane.

Eventually replaced the original NGKs which seemed to last forever. Instead of being over $14 for NGKs, these Autolites were cheap and felt right. The clearance on each plug was 0.046 from the factory, and this motor needs 0.040, so I tweaked it a bit in advance. Surprisingly, working with spark plugs on this car was the easiest of any V-8 or -6 I've had in 30 years. The old candles were very tight so take your time. Blow off dirt before removing bobbins. Be sure to remove the right upper heat…