Great Stuff Marcel,
I've been using the Titan Pro-S 5W-40 since 8000 miles old (now 38,000 & 5 changes since then), glad to see its still No.1! You're correct, it is a full ester synthetic, not a mixed or modified mineral oil which many lesser 'synthetics' atually are (Castrol Included).
I buy 20litres a time from Opie (3 changes for me plus spare), they did me a 30% discount on that amount and free shipping at the time, and I just keep it in the garage till I need it. I'll be doing the same soon as that batch has run out!
Kevin Bird told me to stick with OE spec oil for the Quaife? but I suppose any superior geared diff oil should be ok?
As as you correctly say NEVER use Limited Slip Diff Oil, as the quaife is not a clutch LSD but a geared ATB.
PS - Did you know that Birds are now selling a specially made, finned heatsink-type diff rear cover for the 335i?
(like M3 / M5) good for track work apparently to prevent oil breakdown - sounds like your kind of thing Marcel
