[jparnes1]

I recently did this service for my 2012 35i M Sport and AFAIK there's no DIY for this on the interwebs for a Z4, so here it is.

I was poking around under the car and I noticed that there was a drop of oil hanging off one of the lower water pump bolts. Looking higher up, I saw a lot of grime on top of the pump, all over the front of the engine and below the oil filter housing, where it was the wettest. I change my oil every 5,000 miles and don’t remember topping it off in between so this must be a slow leak. Nonetheless, the oil can degrade the drive belt causing it to break or slip off, so this is a problem that should be fixed promptly.

As it turned out, there was only one tricky part to this job. The oil filter housing is attached to the engine with 3 bolts. One of them is hiding just under the intake manifold. I didn’t have to completely remove the manifold, just undid it and lifted it up enough to get access to the bolt. While this DIY is a little involved, it really wasn’t hard because everything is on top and within easy reach. I took my time and was done in 3 hours. If you feel comfortable wrenching on your car, this is probably in your wheelhouse. And because only an experienced DIYer would attempt this, I’m going to assume you know your way around a car. This DIY is written accordingly. Parts run just $25, plus oil, filter and some coolant.

Tools needed:
8, 10, 11, 13 and 17mm hex sockets, extensions, universal joint, ⅜” and ½” ratchets, torque wrench accurate for 25 NM and below.
5mm hex bit.
E10 and E12 Torx sockets, 25 and 30 Torx bits.
Screwdriver, pick tool, motor oil, coolant.
Line clamps are handy to prevent excess spillage from detached hoses.
Parts: #17222245358 (cooler line O-ring) - two of these
#11428637820 (gasket)
#11428637821 (gasket)

Steps:
1. Remove oil filter and drain oil pan using the 17mm socket. It’s not mandatory to drain the oil, but I was due anyway. It does make things less messy later on though. Replace the drain bolt with a new crush washer and tighten to 25nm, or hand tight and ½ turn.
2. Release the 4 screws with a 5mm hex bit and remove the engine cover. If you have an add-on strut tower brace, that will need to come off too with a 13mm socket.
3. Loosen the four 8mm screws and remove the intake snorkel. The oil filter housing and oil cooler thermostat are circled.