I would think a good car maker like Ford would have done lots of testing, I mean a ton of it. If the oil thinned out of grade causing damage, how could the engine be at fault? Assuming in my example there was no fuel dilution. I'd think the oil company would be at fault. Like it or not I think thin is in, and in the not so distant future you'll see 0w10, and people saying they'll use 0W20 in its place because 0W10 is too thin?
Happy 4th to all,