Synpower 10w-30 or 5w-40?

I'm going to take up about 12 qts of free synpower they got going. I also checked out the UOA's of 5w-40. The UOA's were impressive on this stuff but it sheered down to a 30wt. But these were used in Turbo engines. My question is..which oil is most likely to be sheer stable in a N/A engine? 10w-30 synpower or 5w-40? from the valvoline site, 5w-40 Exceeds European ACEA A3/B3 and all preceeding API Gasoline Engine Oils Since it exceeds A3, I'm leaning toward the 5w-40. But which of these oils will lower my lead wear and stay in grade? opinions? anyone have any specs of these two grades? I guess this thread should be closed cuz the free synpower rebate is not online anymore. I didn't get to print it out yet. I was going to go out today to pick up a case too! The rebate was only posted for one day. I took up on the offer for free maxlife and it was online for months. [Mad] [ May 20, 2004, 02:32 PM: Message edited by: Cutehumor ]