Hey everyone. 98 XC70

I've been running M1 High Mileage xW30 for the past 4 oil changes. I was recently a little low on oil (level was a little less than half of the hash marks on dipstick)...so I stopped into the local walmart. Usually I get oil there. I stumbled across the M1 European 0w40 oil. It meets the A3/B3 recommendation in my manual, specifically states good for turbocharged engines on M1 website....

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil_1_0W-40.aspx

I know nothing like the guys on BITOG with regards to the ins and outs on oil. From self research I understand a primary issue is Shearing. From what I gather the higher the higher variance oils i.e. 0w40 vs lesser i.e. 10w30 are more stable.

So in my poking around on the M1 site it seems like the 0w40 oil meets many Euro car specifications whereas the HM 10w30 is your standard one size fits all specification. I know my "dated" owners guide recommends 10w30 and or 5w40 during the warmer months ( I live in Massachusetts). I guess my hesitation is that 0w40 may not be the best choice, or would it be better?

Has anyone used the 0w40 vs 10w30? Any adverse changes in car performance, increased valve noise? I am willing to try anything but, just passing 203K miles I don't want to start walking the line. On that interesting BITOG site I see some other Volvo owners using the 0w40, but then again there cars are much newer and with LOW miles.

Regards,
Steve