Originally Posted by toyota2bmw

I would NOT do this mod unless you are gearing up for more oill leak problems. For me, that would just create a series of ADDITIONAL multiple points of failure.

Originally Posted by Excession

Originally Posted by BimmerFan52

I too have considered this mod. I believe a big part of the reason BMW did not put the oil cooler on the N62B44 engine is there just isn't the room in an E60 engine bay that there is in the 7 series engine bay. Having changed an alternator on a 545i I can't imagine jamming another component in there. However, I have never looked at a 550i engine, and they obviously figured out how to shoe-horn a cooler in the same engine bay (with a slightly different engine design).

I wish I could find more auto industry scientific studies regarding gasket longevity. I believe the main factors are design of the gaskets (and the 545i lacks here), heat (not good in the 545i) and condition of oil (once oil oxidizes and uses up the alkalinity of the oil additives the oil goes acidic and attacks gaskets making them brittle).

At this point I work to control the only two things I can. Keep the coolant system in good working order and use name brand full synthetic oil and change it frequently.

Regarding aftermarket oil-cooler systems I would be extremely careful to choose a system that has the highest quality fittings with steel reinforced lines and a tried and true design. If a fitting fails allowing a hose to blow off at 100 mph and dump all of your oil I venture to say you'll never pull over in time (even if you notice the dash light while concentrating on the road at high speed).