my 1994 855M turned 325k miles recently (original owner). I have always used Castrol 10-30 plain dino oil, though recently, for kicks (guilt?) I switched to the green "high mileage engine" formula. Keeping the engine oil changed at 5k miles, I have not noticed any negative effects of not using synthetic. I actually use Mobil 1 on my Saab Viggen as it calls for this, but frankly, I'm not so sure it is warranted in the Volvo. It has a big oil pan, and keeping it changed at 5k seems to be doing the trick for me.

The one time I changed oil types to Valvoline (at my dealer's recommmendation) I suddenly sprung a main oil seal leak (at 256k) coincidence? probably, but still hard to ignore. Moral of my story, keep using what has wored so far.

Also, I have used 89 octane for the life of the car, and it has always worked well for me.

I recently bought a "near new, only 100k mi." '99 5 spd V70 and am hoping to log another couple hundred k on it. The 94 still runs true and burns no more oil than when it was new, but it is getting a bit long in the tooth.

Good choice to get the base 5-speed IMHO.

Good luck,
Claude in Maine