As everyone else has mentioned running Shell Rotella T in your gasser will not hurt a thing, the new mandates on cats are just something to make the manufactures look greener, and looking, being greener is great, however in this instance we are talking about a very small increase in problems using these oils with zink, or whatever it is causing the problems in cats when a car consumes oil. I have run the Shell Rotella, and the Rotella T in all manner of engines without any problems... You may decrease your cat life after 200k or so I'm not up on the specifics, but we have come so far with oils, cats, emissions that manufactures are really having to reach to get any gain right now. Cats are a emission system that is mandated by good old government to last a absurb number of miles, or time (which it should be, this keeps pollution out of the air, they are expensive when purchased new because of the precious metals they contain) so the car manufactures reach for that little bit more to stretch them as far as they can, however we as Americans are the type that when you place a need for a product that free enterprise will take over, and I think eventually we will see a add package that will once again cover a broad range of engine types from the new roller type valve/cam systems, to the old flat tappet high spring pressure high horse power hotrods. This is just my rambling opinion, as of now the newer oils are still better setup for our newer engine types with roller type cam/valve systems, these type systems produce greater economy, much easier on oil (this is why the long drain intervals) and in my opinion a better overall engine that produces less pollution, most of the time now with engine internals greater economy equates to a longer lasting, and even more horsepower producing engine (excluding the smog pumped junk for the 70's era). Sorry for the long rambling post, but I really think the drive for greener engines, longer drain intervals, 5w-20 oils even are producing better designed engines, and Shell Rotella T type oils are still great oils that can serve these engines perfect !!