You must have been editing while I wrote. You have the advice above of an owner of your type of engine. Ask your dealer, but unless he tells you different, I'd add it when you do the 3750 change.
My answer to your original email...
It is Castrol synthetic motor oil produced in Germany and now imported into the US. It is a 0W30 and has an excellent reputation among some, maybe many, on this board. It was sold outside of North America under the name of Castrol SLX (we got into the mode of calling the US version German Castrol or "GC") and has now been upstaged outside the US by the Castrol RS line and a new long drain interval product called by a couple of names: Castrol DCO Topup and Castrol SLX LongTec (they are MB 229.5 rated). SLX is rated: API SL/CF; ACEA A3/B3 B4-98;VW 502.00, 505.00 and 503.01; BMW LONGLIFE-01; MB 229.1 and 229.3 and is Porsche Approved. It has gained an excellent reputation from Used Oil Analyses cited on this board and it has the side eccentricities of being green in color and smelling to some like German Gummi Bears. It is available at some Autozones around the US and at Walmart in Canada. Hope this catches you up.
[ June 13, 2004, 10:51 PM: Message edited by: pscholte ]