On the assumption that fuel injector cleaner should be used periodically, does it matter when in the oil change interval it is added? I was thinking that since it is supposed to clean things out that maybe one should wait until close to changing the oil to do this so that any extra contaminants that might have gotten in there from the cleaning could get immediately drained and not circulate around for 7 to 10 thousand miles. Would certainly appreciate people's experience and insight here. Also, how often would one run this stuff? I just got a 2012 Cadillac SRX with 35k and have no idea how the first owner drove or what kind of gas he used. Am experiencing slight pinging but haven't used any GM fuel injector cleaner yet because the oil life monitor is at over 90% due to my above expressed concern about doing it so early in the oil change interval. Also, whenever one does this, is the GM product the only safe one to use? Owners manual says only use the GM stuff and this is the first manual that has ever said anything at all about which product to use. Am wondering if it is just marketing or whether there is some real substance to that recommendation based on some particular idiosyncrasy of the GM fuel system (sort of like only use Honda p/s fluid in a Honda power steering unit). Thanks in advance.