has anybody used Autolite XP3924 spark plugs instead of the NGK IFR5N10 ?

 

Why are you considering this? NGK and Denso iridium plugs are world-class. Anything else would be a step down....

 

I have been using Autolite plugs in cars for over 40 years. In both street and competition and with engines that will strain them much more than the Jag ever will I consider them to be a first class brand. The 3924 is a top line Iridium plug available from a local supplier while I would have to order the NGKs. I am not aware of any local supplier that carries Denso . I am aware that some vehicles are very "particular" about plugs so I thought I would ask.

I would not , for example use any sort of Bosch plug. I have replaced more Bosch plugs in friends's cars than any other brand over the years.

 

Talked to my supplier. He can get Denso iridium plugs SK16PR-L11 has anybody used these ?

 

Just from my experience from years back on motorcycles. I wouldn't put Denso in a roller skate. Seen to many of them fail. NGK was always the plug of choice, for bikes. I agree with Barry on this one. Autolite is one of the best most reliable plugs on the market, bar none. As "John Force" said "they keep this Monster Lit". On another point I don't like platinum anything! Haven't had much experience with the newer Iridium Plugs yet. Just my thoughts.

Jack

 

If you decide on the Autolite's, you may want to check if there is a factory rebate. I bought the XP3923 plugs (for my XKR) from Rockauto for 35.99 (incld shipping). After $2/plug mail in rebate, I paid just under $2/plug.
From my quality standpoint, it has been decades since I could tell any difference in any recommended plugs.

 

Same here, They work fine.

 

No complaints in running Autolite coppers, platinums or iridiums in ANYTHING. They get my endorsement.

 

Ordered the Autolites and assorted other stuff for the winter project. Looking forward to getting at it