In person, does plug #1 look very white in comparison to plug #4?
Also, I've heard that oil (on #6) can find it's way above the spark plug. Personally, I've never had that problem, but a DIY on Pelican Parts says that it's not necessarily a huge deal.
For reference, I always use Mobil Clean 5000 (10W-40). I change my oil every 2500 - 3000 miles. My car has 146,000 miles on it and the car burns absolutely no oil, but then again, that could be an M42 thing.
Edit: Can I ask why you changed to Bosch +4 plugs?
thanks mullet. do you happen to have a link for that diy on pelican or the name of the article?
plugs 1 and 4 look pretty much the same. it may look more white in the pic because i might have used a flash on that one. i change my oil every 3k miles too, and it is 10-30, i have no idea why i thought it was 5-30. your M42 is a good bit more technically advanced than my M20 from what i understand so maybe that is a factor too.
i knew someone was gonna ask about the +4's. i did a lot of looking around as to why people didnt like the +4's and from what i found it was mostly people with M5x engines with the ignition coils/plasma injectors or whatever the heck they have. other people have used them in their M20's and M30's and they were ok. in my previous E30 i tried both bosch silver's and the +4's and i noticed slightly better performance (altho this is relative and IMHO i suppose), but no negative effects have come up in the 60k miles plus that i have used them for.
thanks elsa, i appreciate it. lemme know what your friend says.
I'm not too good at this kind of thing, but a few of them look like ash fouling, from burning oil and other gasoline additives. Doesn't look like they're running hot tho. At your mileage, there will definitely be some wear on the rings and cylinder walls, but that's to be expected. Try doing a compression or better yet, a leak down test. Maybe your oil is breaking down fast, try a heavier weight?