Oil "detergent"

[Bob Spidell <spidell@hpcc01.corp.hp.com>]

A question on the mineral/synthetic/engine/motor/transmission/overdrive oil
thread: do the modern automotive engine oils actually use detergents, or 
dispersants?  I know detergents are not used in aircraft engine oils, in
lieu of ashless dispersants, signified by "AD" on the bottle.  Apparently,
detergents in oil can cause problems, esp. in aircraft engines.

I always thought the "W" in XXW-YY oils meant weight.

regards,
bs