Not sure if this post got thru. Should I buy spark plugs from Volvo or can I just get them from a retail store?
2001 S40, 4 cyl 101k miles.

 

That is a personal choice. The NGK Iridiums are very nice though. About the same price as the Volvo plugs.

 

Whichever brand you are most comfortable with, as long as it is a high quality brand (NGK, Bosch).

 

from experience with the s40 and from doing the mods, I've come to the conclusion that you cant go wrong with genuine volvo oems, whatever you do dont get the bosch. I went to the groton store and got new oem plugs wires and coils for a reasonable price. The life on the oems are twice as long as that of the ngk iridiums...

 

This is a MUCH discussed question all over the net. The bottom line seems to be: If you are intent on going to other than only OEM plugs, the NGK Iridium are the only ones to try. But provide no advantage over Volvo's. Even on many of the "speed" sites, the street racers stick with the OEMs due to many, many problems coming from other plugs. The cars seem to be very tempermental. You can buy OEM Volvo plugs from the vendors on here cheaper than the dealer, even with shipping.