Conversation Between SR20DEN and ajahearn

Hoping to get some advice. Over the years of belonging to the Maxima.org bb you have been one of the guys who clearly knew what they were doing. I'm more of a weekend DIY and would not attempt things like changing out my clutch, etc. but I'm more than a oil changer guy. I have 2002 SE 6SP that has been recently throwing P0302 codes (72K miles). I pulled the plug and it is a bit covered in oil. I checked #4 and #6 and they appear okay. So I decided to try a hotter plug and things seem to be working out well (even my gas mileage has gone up). I've read several postings say that Nissan tends to run their engines rich so I figure this is probably/hopefully a side affect of age. What I'd like to know from you is if there is any benefit to changing out the remaining plugs for hotter plugs? I life in Northern CA and we mostly have hot days (today was 91). The winters never get colder than at most freezing and even then only for a few days. Its an easy enough thing for me to try anyways. Anyways if you are out there and wouldn't mind a response I would appreciate it. Thanks for all your postings otherwise. Gave me the impetus to try more than brakes and oil.