Northstar Engines and System Technical Discussion Discussion, Popular choice for spark plugs in my 99 STS??? in Cadillac Engine Technical Discussion; well its about time to change my factory spark plugs in my 99 N*...what seems to be the popular choice ...
Re: Popular choice for spark plugs in my 99 STS???
Originally Posted by 1fastSTS
well its about time to change my factory spark plugs in my 99 N*...what seems to be the popular choice that everyone goes with now over the factory stock ones....
any better AC-Delco ones?
AC Delco 41-950s are spec'd for your car. They are double-platinum and the engine was tested using those plugs, so I would definitely recommend sticking with those. If you want to try something different, NGK double platinums, Autolite double platinums, or AC Delco Iridium plugs might be OK choices, but I don't know if the heat ranges for any of those other plugs will match up with what the engine requires. You can put whatever you want in there and they will probably work, but it's a question of how well will they work and for how long. For the sake of saving time and money, it would be my choice to stick with the 41-950s.