92 740: which spark plug is best?

I want to replace the OEM type plugs with premium ones. Maybe Bosch
Platinum or SplitFire. Whats the best?

 

Use good old ordinary NGK plugs, I've had great luck with those, the
"premium" plugs are a scam, especially if you have a turbo, my friend
spent weeks trying to track down why his Merkur turbo would start
bucking and misfiring like crazy under boost, finally a mechanic
suggested to replace the Bosch Platinums with plain NGK plugs and the
problem went away entirely. Volvo is not a cheap brand, they chose the
OEM plugs they did because they work well in the application, not
because they're cheap.

 

I am using a bosch 3 electrode plug and they work well .Not expensive and I
noticed an instant difference .When they need replacing I will know if they
strip the treads as has been my previous experience in other cars .

 

I've been very happy with NGK plugs in Volvos, both the regular kind if
you change every 20k miles or so or the more expensive Iridium type if
you want to go 50k miles or more.

Recently the Kragen/Checker/etc. chain had the NGK IX Iridiums on sale
for $1.99 each, which would be a great deal on a great spark plug.

John

 

I'm not a fan of Bosch Platinums. Their small electrode tip seems prone
to trouble in some applications. The other makers all have a much more
substantial center electrode in their platinum and iridium plugs than
does Bosch.

John

 

In this case we decided what must have been happening is the boosted air
rushing into the cylinders was simply blowing out the spark. I can't
think of anything else that would cause it to run as badly as it did.
Idled fine with the platinums but once the boost came up all hell broke
loose.