IPDUSA.com has alot of aftermarket Volvo products. They sell a tool specifically designed to remove the plastic oil filter canister, but...

I use a common oil filter strap wrench to loosen the plastic canister. It is a good idea to have an extra canister on hand if you need one.

My dealer sells the filter elements for about $10 and a combo pack of element and canister for $14. I have an extra canister if I break the original.

I drive alot and change my oil about every 6-8 weeks (3k-5K miles). I buy the MANN oil filter elements from IPD (about $5-$6).

And especially on a turbo USE SYNTHETIC oil (with a quart of regular oil).

I have a 1994 850 with 230,000 miles on it (all original no engine work).

Tighten the drain plug snug but don't feel like you have to all your strength. Ive never had the drain plug leak.

My 850 is non-turbo and I haven't yet figured the best way to chenge the intercooler oil. So I just change the oil often.

Good Luck
1994 850 5 sp stick
1999 S70 5 sp stick
2001 V70 T5 5 speed stick