How you guys feel using 5W-30? I have big concern if it's going to hold all the stress that is been exposed in this engine. All European car makers have been recommending 0W-40 (not really available in LOW ASH formula) or 5W-40 for their turbo engines or high performance engines. I am debating if I should switch to higher weight. I know most of this is part of the CAFE crap we have been exposed to, but why sacrificing engine longevity when car already beets the gasoline couterparts in fuel efficiency by big margin.