Hello -- I know this might be a common question, but I can't find it on the forum, so here goes: I've always used conventional Castrol 5w-30 motor oil in my 2010 XC70, and always at the dealer. Now the dealer says they've phased out conventional and only use synthetic motor oil. I'm concerned. At 120,000 miles, my car has never leaked -- although it does consume about a quart per 800 miles in blow by -- and I'm worried that switching to Castol Edge (synthetic) may harm the seals or increase the blow by and oil loss. Generally, people say synthetic is "better." What do you say ... am I worried for no good reason? Should i continue to use conventional, since I've never had any problem? Please let me know you opinions, and thanks! -- CFH