The Subaru Boxer engine sure is quieter with this oil at startup...used to sound like someone dropped a bag of bolts on the floor! "Well that's just the way they are!" Nope, it apparently doesn't have to make such a racket. I run it in a Toyota 3.5 V6 as well. No change to MPG in either vehicle over the 0w20 they are spec'd to use. I'm going to run the Subaru to the recommended 6,000 miles interval with ESP Ow30, I had been running 5,000 miles just to make it easy to remember. My memory is better than that and I hate to short-run good oil...best to get the miles from it that it has to give, while staying within spec'd 6,000 miles to maintain warranty.