I have an 08 535xi.

My Oil Cooler Housing Gasket is leaking, which is common on the N54s. I'm not sure if the OFHG is also leaking, but obviously it's a lot more work to replace the OFHG than the OCHG. Can I replace the OCHG first, and if need be replace the OFHG later? or, will the OCHG have to come off in order to replace the OFHG?

 

Wow, you're using a lot of abbreviations there.. to make life simple, I'm sure you're talking about the front one vs the one on the engine. So yes you can change the front one first without the second one. But.. if you went to the effort of changing the second one, you'd be an idiot not to change the front one

I changed the front one (oil cooler housing gasket? ) Which didn't solve my problem to my disappointment, so yes.. had to go back and take a ton more apart just to change the oil filter housing gasket.