I`ve just bought a 1997 850 awd (paid £3500 for it-good or bad price?)its done 72000 miles,i want to change the oil but am at a total loss as what to use mineral, semi synthetic or fully synthetic. What do u people use on your turbo engines-have heard some bad reports about switching to fully synthetic. I have also got a leak, looks like turbo return line, is this as straightforward as it sounds to replace or am i likely to have problems? any help on these matters would be appreciated.

Congratulations on your purchase. In US, furst AWD's were in '98 V and S70's. I didn';t know there were any 850's AWD's anywhere. Where are you located? Anyway, My sense of oil consensus is that Dino is fine so long as you change it fre3quently, and there is no particular issue with changing to synthetic. I run Mobil 1 synthetic in everything most of the time, and have changed dino cars over to synthetic when they had as much as 170k miles on them, with no problems or leaks. I really like the ciold weather characteristics of synthetic, since it doesn't thicken up when it gets cold. This makes cold weather starts much faster, with less battery drain and much less internal engine wear at start. Something like 90% of engine wear is often reported to occur in the first couple of minutes of each use, and this alone makes the added cost seem OK. Also, there are a fair number of proponentw of slightly longer drain intervals with synthetic, say 5,000 miles versus 3,000 for dino. for teh oil leak, go to volvospeed.com, enter the Bay 13 section (repairs and maintenance tips and write-ups) and you will find lots of good tips, including one on teh turbo return leak and how to fix in detail. It is not a big deal. Good luck.
--
Mike Sullivan ('91 745 (171k), '93 965 (147k), '95 855T (60k), '98 V70XC (78k). Past Volvo's: '85 744 (256k), '86 245 (165k), '86 245 (195k), '88 745 (208k).

I agree with the Mobil 1 Full Synthetic oil, great stuff. I have used this on a variety of cars with great results. I switched my 95 855T to synthetic when I purchased it 3 1/2 yrs ago with 70k miles. I just had some new struts/shocks installed this week & was able to get a good look under the car while it was on the rack. Currently with a 130k miles, it has no oil leaks including the turbo drain line. (Which I was expecting to find a leak starting because of the mileage/age)

My understanding is that synthetic oil has more "detergents" & really keeps things clean. On higher mileage/older vehicles switching to synthetic can clean out the "gunk" & sludge inside which sometimes is all thats preventing a leak on a worn/old gaskets. (Hence the myth of synthetic oil causing leaks) If you switch, I suggest you do your first oil change earlier because of the sludge it will clean up.