Mysterious oil leak

uberchris · 11-20-2021, 01:34 AM

I've got a slow oil leak that I am having a hard time pinning down on my 2011 X5 35i (N55). It is most visible on the very bottom where the engine meets the transmission. There may be some oil on the passenger side of the engine, but I can't see very far up from the bottom to see where that might be coming from.

I took a quick video here:

Note that I cleaned the bottom of the engine thoroughly yesterday, so the oil you see is from one day.

I have already replaced the oil filter housing gasket and valve cover gasket and confirmed these are not leaking. Any ideas what to check next?

Thecastle · 11-20-2021, 08:33 AM

Put some die in the oil and look for the source.

Given its at the transmissions / engine interface and if its actually oil, then its likely a rear main seal. Or its dripping from above someware, hence use the die. Any mechanic will be able to locate this for you.

11-20-2021, 01:34 AM	#1
uberchris Registered 3 Rep 4 Posts Drives: 2011 X5 35i, 2005 M3 Join Date: Feb 2019 Location: Seattle iTrader: (0)	Mysterious oil leak I've got a slow oil leak that I am having a hard time pinning down on my 2011 X5 35i (N55). It is most visible on the very bottom where the engine meets the transmission. There may be some oil on the passenger side of the engine, but I can't see very far up from the bottom to see where that might be coming from. I took a quick video here: Note that I cleaned the bottom of the engine thoroughly yesterday, so the oil you see is from one day. I have already replaced the oil filter housing gasket and valve cover gasket and confirmed these are not leaking. Any ideas what to check next?
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11-20-2021, 08:33 AM	#2
Thecastle Major 307 Rep 1,146 Posts Drives: F10 550i Join Date: Apr 2015 Location: Houston, TX iTrader: (0) Garage List 2020 BMW M340i [0.00] 2019 RAM 3500 [0.00] 2020 BMW X3 [0.00] 2016 BMW 550i [0.00] 2000 Ford F450 7.3l ... [0.00]	Put some die in the oil and look for the source. Given its at the transmissions / engine interface and if its actually oil, then its likely a rear main seal. Or its dripping from above someware, hence use the die. Any mechanic will be able to locate this for you.
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