1987 Jaguar XJ6 Vanden Plas Spark Plug

UPDATE

Recently had the Autolite Platinum Plus plugs replaced with the original Champion plugs. No question all is better...idle...power...increased freeway mileage numbers. The 4.2 FI engine does indeed prefer the old fashoined copper plug.

Scott W. Moseley

been using Splitfire plugs since 1988, in all my cars, never experienced anything bad, wasn't aware of any quality problems. I do know the competitors complained to the federal government about Splitfire's claims, then a lawsuit was filed which forced Splitfire to stop claiming "better gas mileage" and "higher horsepower/response", and their Patent was cancelled, something like that... But then came Bosch and copied their split tip!!, and a bit later most everyone else started offering a split tip too! I stuck with Splitfires through it all.
I thought Splitfire had been unfairly treated. Nobody can claim "better quality" seems to me, just recently someone was pulling an NGK plug and it broke in two, you can guess where the bottom half fell into.

I use NGK V groove or Irridium, both work good. I do know Splitfire had problems with quality initially and were more expensive, however perhaps that problem has been solved. The price seems more reasonable now also. Perhaps I shall try a set next time I need some. Till then its NGK for a long time with the Irridium's....... Art

Edited on 2008-02-11 8:51:11

errr, neither.....I stopped using those a long time ago.

try the Splitfire part number SF6E. AutoZone. Special Order. $2.99 ea. or thereabouts.

30 Day Return warranty from manufacturer if you don't like them. I use the above plugs in both my 1965 3.8 and 1984 4.2 engines. They come factory-gapped at .035. I get faster starts, better gas mileage, better response when I step on it, and no fouling. Try THAT with the other brands.

And by the way, it doesn't matter if your car is a Vanden Plas or a "Base" XJ-6. Same engine. Only differences are in interior trim and a few badges.