Question for oil experts?

Just today I saw (in wal-mart) that they sell an oil targeted to
Pre-1988 cars, and it is an API SF rating.

What's the deal with that? Not being a chemist, I've been
putting the new stuff (now at API SM rating) in the car thinking
new oil is better at everything. Is there some reason to use
old formulas?

They even have a warning not to use it in newer engines
designed for newer ratings, which I can understand.

I have never seen this oil because I will NEVER, EVER, shop at Wal Mart.

Cheers, Elliot

Ben listening to the union funded anti Walmart media campain a little to much Elliot???

they dont sell metamucil do they?

Older oils used an additive that was detrimental to catalytic convertors and O2 sensors, but they have been around longer than 1988 so I got nothing.
Prolly the same thing as almost every new other oil product, it's all marketing and hype, no substance.

You don't have to listen to the librul media to know Walmart sucks ass.

I don't know, it seems if they are trying to say a particular old spec oil is better
for your old engine, they should elaborate, or try to tell us what is going to
happen if we keep using the new stuff. Crap, I sometimes buy the industrial
turbo diesel spec oil for the 914-6. I must really be livin' on the edge.

Did they turn down your application as door greeter?

ROFLMAO

There was a good article in Hot rod Magazine (June or July) on this topic. The problem deals with solid tappets and cam wear. Older oils contained aditives that when burned damage the air and your cat and o2 sensors. These additives are being phased out. The magazine suggested a Shell oil used in Diesels that still contain these additives. I started using Royal Purple. So far no problems except in the wallet.