Hello All,
I recently reached a 100k with my 2004 5er, and was thinking of starting using "castrol gtx high mileage" oil. I heard that it helps to protect a little better than your normal oil. But I have two questions. 1.) Is this brand still a syntheic oil and 2.) In the past I've only used the normal castrol syntheic oil, would the change of oil be harmful.
Please chime in with your thoughts and suggestions.

If the Castrol synthetic has served you well - I'd stick with it. I believe that high mileage oil is a conventional. IMHO, 100K on a modern engine is not all that "high mileage" [

stick with the red labeled castrol sunthetic 0w30.

PS you posted in the F10 forum (but you are talking about a e60...)

Thanks guys.