It seems like about a year ago I read on this forum that Shell RT 5-40 was hard on cat's. Is this still a fact or has this changed since it now meets SM spec? Is there any risk involved in using it? I'd like to try it in my Subie Forester Turbo or would I be better off with something else. I've been using Valvoline Synpower 5-30. Thx for any opinions.
Gene
Gene