Greetings,
I have a '98 V70 base (NA) with almost 250,000 miles on it. Still runs well and has given us few problems since we bough it in '14 with 199K miles (for $1500!). I'd like to keep it going for as long as possible. I have been careful about oil changes every 5000 miles (5/30 conventional oil). The car is in Maine with my daughter: cold winters and some hot summer days). I have often wondered about the wisdom of oil and fuel system treatments and additives, such as Sea Foam or Lucas Oil stabilizer. I have seen a few videos that do not appear to be advertisements that seem to reveal some advantage to these products. I am stuck between experimental preventative maintenance using these (alone or in combination) or continuing my "if it ain't broke, don't fix it" approach.

Any thoughts about whether these products are helpful? Since I'm on the topic, what about for turbo engines (XC70 and 90 w/5 cyl turbos)? Thank you!