N54 low oil pressure

[jdconner19]

I’m new to this site and to the bmw brand so I’m not sure if this is the right place for this. With that being said, I did an oil change a couple weeks ago on my 07 335i and I now have a low oil pressure light. I scanned the car and the only code I’m getting is a bad oil level sensor. The light popped up after idling the car for about 30 minutes (it was pouring rain and I was waiting for it to let off before leaving work). I have checked and have no major oil leaks and the car was full of oil. I drained it and put fresh oil in just to be sure. I also put a new oil level sensor in the car. No metal shavings or signs of bad bearings in the motor. No lights popped up in the 2 weeks before letting it sit and idle the day I first saw the low oil pressure light. The light doesn’t pop up when the car is cold either. I had 5w-30 Castrol Edge in the car when the light came up. Only change is that the weather has been warmer, around 80*f the day the light came on. Should I use a higher weight oil for warm weather or am I looking at something a little more catastrophic?

[pbonsalb]

N54 are great motors but require a lot of sorting out at this age unless fantastically maintained. Most are not fantastically maintained. I had one for 10 years and still maintain it for the friend I gave it to.

I am having a hard time figuring out why you have low oil pressure after an oil change. How long have you owned the car? If this is your first oil change, do you know what oil was in it — weight and mileage? Maybe the PO had a problem and ran thicker oil to mask it.

What weight did you put in? I used 0W40 and 5W50. Given your oil light, I would go 5W40. What oil filter did you use? Was the one you removed for the oil change wrinkled and bent or were the pleats totally straight?

More catastrophic is possible, unfortunately. Bimmerworld recommends rod bearing replacement at 75k. I changed mine at 150k and they looked fair. I have not read much of oil pumps failing — I did a lot of preventative maintenance — rod bearings, turbos, turbo oil and coolant lines, water pump, thermostat, etc., but never the oil pump. I did install a crank guard plate behind the crank pulley and did buy a new oil filter housing — oil leaking on the front of the engine gets kn the belt and can ruin it. The result can be catastrophic if the belt breaks or frays and gets through the main seal.

[jdconner19]

I’ve owned the car for 3 months now. It has 170k miles. PO changed the oil not long before I bought it from him. He said he’s only ever used 5w-30 castrol in it, so that’s what I put back in it. The oil filter (I put in) was a little wrinkled when I took it out to check it and replace. I’ll try a little heavier oil. The PO didn’t drive the car often so he may not have noticed the lighter weight oil having an issue. I didn’t have any issues until the weather warmed up.

[M5Rick]

5w30? Just no. Its for run of the mill small shopping cars like Fords,VW's and Nissans.

[jdconner19]

I was told that is what bmw recommends for these cars. 5w-30 castrol and that’s all the PO said he put in the car. I will try 5w-40

[335i54n]

actually diagnose it, hook up a hf gauge (30). if bad, likely its had a belt sucked in and they never dropped the pan and cleaned the pickup.

[jdconner19]

I stuck a camera in the pan and looked at the oil pump screen and for any buildup in the motor when I took the level sensor out. The motor is clean.

[335i54n]

a gauge will tell you mechanical or electrical (uncommon) issue

[pbonsalb]

Based on what you write about inspecting inside the pan, 5W40 is worth a try, but an N54 in good condition won’t trigger the oil light at idle with 5W30.

You are sure the light is for oil pressure and not low oil? I think the yellow light with the oil can is for the level. It is not uncommon after changing oil to not immediately get an accurate reading. There may be a red light for oil pressure but I am not sure.

[jdconner19]

I changed the oil to 5w-40 and drove it home (about a 45 minute drive). So far the low oil pressure light on the idrive has not come back. I let it idle for about 5-10 minutes once I got home and all was good. I appreciate the help and suggestions.

[Leucosticte]

Check the oil pressure with a gauge and rule out the wiring/oil pressure switch. I've heard of rare instances where the switch itself fails.

[pbonsalb]

Originally Posted by jdconner19

I changed the oil to 5w-40 and drove it home (about a 45 minute drive). So far the low oil pressure light on the idrive has not come back. I let it idle for about 5-10 minutes once I got home and all was good. I appreciate the help and suggestions.

Fresh oil will thin out, so the light may come back on. I would call this a bandaid rather than a long term fix on a 17 year old N54 with 170k miles. I do recall my E36 M3 owners manual saying that the oil light may flicker at idle speed. The safest thing is, as others recommend, measuring oil pressure.

[whyzee125]

I would've suspected belt as well but if that's clean that's a good thing. While 5w40 may not show the same issue, that's not a true fix.

What oil filter did you use? Some aftermarket ones tend to scrunch up and may be due to not enough flow. Use the $7 Mann filters if you didn't already and see if that changes anything.