5 Different oil leaks!!


Jan 30, 2018
2007 E90 335xi 6mt, 2016 M2
Hi Everyone,
I am not new (lost old screen name). But anyway, I am finally getting around to my pure stage 2 turbo build! I have notice there seem to caked on oil all over the engine (see pictures). So far I have confirmed oil leaking from Front main seal, rear main seal (or maybe oil pan gasket), Oil filter housing, and pretty sure the head gasket. All the listed above seals are getting changed regardless. The car was starting to go through about a 1q of oil every 1k before I started ripping the car apart.
But any idea on WTF is causing this much oil leaking? Thanks

Forgot to add car has 143k ish motor has 60k ish
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New Member
Jan 30, 2018
E93 N54
I believe that our overly high operating temps cause the seals to wear prematurely. Yes, Porsche turbos run even hotter, but they also suffer from various oil seal failures.
Oil temps at 250F are just too high. BMW does it mainly for fuel efficiency and emissions.
Depending on your climate and season, you can get an oil bypass valve and use MHD to set the coolant target temps to be much lower. Lower water temps have helped my oil temps stay much lower, around 220F in regular driving and 230F in spirited driving.
With your engine already out, you can consider changing even the turbo line seals. Flush the oil lines to make sure there's nothing caking up inside. Change the valve cover and seal. A lot of leakage comes from the valve cover and drips down, making it seem like it's coming from elsewhere. If you're sure the head gasket is really leaking (not common on our platform) and you're going to take off the head, you can also consider changing out the valve guide seals. Then change the cam ledge seals (ie rectangrings) to teflon ones.
Seals are not expensive and really easy to change with the engine out. With the engine back in, many of the seals are extremely painful to replace.


May 9, 2017
Rhode Island
07 e60
Looks like that engine has never seen a pressure washer. One thing that I've always done, keeping an engine and the radiators clean of all that road grime. The panels that protect the bay, are also a nice trap to collect all that crap that you run over. Anyway, there are numerous engines that don't leak for miles, some loose engines at 30k from a $10 gasket and a $40 belt. There isn't a gasket on this earth that won't break down in time. Most main seals have rubber, plastic, and metal in them, all have one thing in common, heat. Heat will eventually break down rubber over time, and with petroleum products,the heat will cook the rubber breaking it down. Unfortunately, it's all part of maintaince and will require attention.


Nov 18, 2017
Down under
335i DCT 2009
I was reading the other day that the water pumps have gasket material that doesn’t like oil, breaks down swells up and eventually fails. Who put something like that in an engine bay?