Greetings. New member and (gulp) first post here.
I have an 02 3-series BMW with 120K, and a 06 Tacoma with 51K. I am the sole owner of the Tacoma, and I bought the BMW @ 88K.
The BMW has always gotten Mobile 1 5W-30 synthetic with a Delco filter, approximately ever 5K. The Tacoma gets regular Mobil 5W-30 and a Delco filter, approximately ever 4K. I'm not doing my own changes since I have a trusted shop down the street.
I do a lot of work on my own vehicles and want them to last. Hence, I have started doing UOA on the Tacoma and have done UOA on the transmission fluid on the BMW, but not the oil yet. I am strongly considering switching both vehicles to AMSoil (European Car Formula 5W-30 Synthetic Motor Oil for the BMW; SAE 5W-30 XL Extended Life Synthetic Motor Oil for the Tacoma) and am looking for input from all you guys that know much more than I do. My main questions are:
(1) Is it foolish to change oil type/brand on a higher mileage engine? The BMW engine (M54 series) is tough and wears well so I am guessing, 'no'.
(2) I would run the oil longer, say probably 8K. I'm guessing I'd best do a filter change and top off the oil mid-way through that oil change interval.
(3) Is going to AMSoil overkill when I am already using Mobil 1 5W-30 synthetic in the BMW?