Turns out that the answer is not much of a challenge at all. The E39 M5 guys have this thing suitcased. Swapping in the gulf oil filter is plug and play, the hoses, AN lines and adapters are all well known and available, and there are good after market cooler options or OEM from other BMW platforms. OEM models are quite expensive unless a good one can be found used.

The problem now comes down finding a filter housing because the BMW housings seem to be all gone, and Bentley has stopped sourcing their, identical, version within the last few months. I finally found one in the UK at a Bentley/Rolls parts dealer. It’s $44 bucks versus $180 or so, depending on the seller.

I’m going with a 10 or 14 row Setrab I think (slim line) so mount it up front in my bumper and clear the aux fan shroud.

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Current
Original owner 2002 E53 X5 4.4i to 4.6i swap
2026 G80 M3 6 spd
2025 G06 X5 50e
Former
1972 Audi Fox
1986 Saab 900S
1996 BMW Z3
1998 BMW E36 M3 Sedan
2004 BMW E46 M3
2006 Audi A3 Quatro
1993 Mopar 318 Jeep Grand Cherokee
2015 V6 Jeep Grand Cherokee