Jim H and all,
One of the diagrams on Jim's link seems to allay a concern I've had as I've watched my temperature gauge creep to 110C during summer traffic in Florida. It looks as though the oil is ok through about 140C, which gives some cushion if the temperature of the hottest parts of the engine are at or below 140C when the gauge says 110C.
FWIW, my manual (1992 600 SEL) says to change the oil and filter every 3,000 miles.
[This message has been edited by dfndr (edited 10-26-2000).]