I have an 05 545i 6spd man...with 91600mi.... been running great...had a rt bank emissions light come on...but flushed out vacum lines with seafoam...all good
well now changed oil with recommended amsoil and mann filter...been using amsoil for yrs in other cars...low oil light is coming on and going off...anything below 2200 rpm casual city driving...no light...freeway driving and medium acceleration and light comes on and goes off....

Replaced oil pressure switch $12. ...no change....replaced 6 oil check valves...found mechanic bulletin on possible failure. ..all looked good but replaced anyway cause of bulletin. ..$140...preventive maintenance. ...mann filter and oe filter are different. ..so I replaced with oe filter

Still have light coming on and goin off at 3 k rpm...not enjoying this wonderful car at the moment. ...please help?!

 

So now im thinking drop oil pan and check things out? Thoughts?

 

what weight oil you using?

normally if a car cant hold oil pressure, it occurs when hot and at low rpm or idle. but you're saying that the light comes on at higher rpm? weird.

 

5-40 Europian formula amsoil....wierd right...higher rpm ?

May just dump oil and get castrol...see how it does....always heard bmw was picky

 

i wouldnt think that the oil would cause this issue, unless its on the upper end of the 40 weight scale, and not flowing as smooth, and forcing open bypasses??

 

Thanks for your input....goin to actually gonto dealer tommorrow and get it from them....reading that retail catrol is not same as bmw castrol....better safe than sorry....live and learn....at least no damage done as the oil is clean...just some $$ and some knowledge

 

Well there is definitely something to be said about the engineering partnerships between castrol and bmw....put bmw dealer oil in and runs like new...no bells...just a blast....

 

I very seriously doubt you are getting low oil pressure from 5W-40. I run 0W-40 Mobil 1 in both my N52 engines without a problem. Would be good to check the actual oil pressure. If there really is an issue, you have something else wrong...clogged oil pickup strainer, oil pump in need or rebuild/replacement, etc.

 

Strangest thing ive ever seen....change to amsoil and car acts fidgety. ...put bmw castrol in and it moves and groves without a peep....just wont deviate from it on rhis car...use amsoil in other three for years with no issues