DMAX

How often do you guys change your spark plugs. Also whats recomended for 502 efi gen 6 Thanks.

BajaRunner

once a year for me.

GOODT

in most cases it should be at start of season after firing up and burning off the fogging oil, in the case of the 496 with platnum plugs 85 - 100 hrs is what merc recomends

Outdrive1

Delco mr43t's is what I always used in mine. 100 hours or so is probably ok.

GOODT

thats way too many hrs for those plugs

Magic Medicine

MR43T is what you need. I change mine once a year, I have a 500efi.