Originally Posted by TrackRat
Until then use the BMW approved Castrol 10W-60 product to protect your engine and your warranty.
The reason I'll keep using TWS is to conserve my warranty. BMW doesn't have any incentive to 'approve' other oils since they're making money off TWS. And don't think they're too worried about your engine when they're 'recommending' oil changes every 15K miles, just because they're paying for that.