Originally Posted by kiwi29
What exactly do you mean by noisy?
It was mechanical "white" noise. If you google something like "Mobil1 noise" you'll see tons of stuff. Some people believe it's BS because it doesn't happen on their engine. Others go on and on about it.
On my M52, it was dramatic. On Mobil1 the engine drowned out a slight lifter tick and everything else under the hood. Running through the rev range on the road sounded kind of like it was doing it but it wasn't happy at high revs. Lab analysis of the used oil came back great for oil condition and wear metals. The oil had sheared significantly from being a light 40 weight to a mid-weight 30 though.
On anything but Mobil1, suddenly the slight lifter tick was prominent, I could hear power steering and alternator whirring, and I could talk to someone comfortably in my attached garage with the hood up. On the road as I ran up to high revs I could most only hear intake and exhaust instead of all of the other mechanical hash.
I believe the phenomenon started during one of the early 2000s reformulations of Mobil1 (like change from TriSyn to SuperSyn or something). I was a die-hard M1 fan and ran it in a 1990 Acura (5W30) and 1992 Porsche (15W50 red cap) too. I had noticed that both seemed to get noisy but didn't associate it with the oil. I just thought they were "getting old". The Acura Integra picked up a lower frequency rumbly noise from the valvetrain. The Porsche was more general noise like the BMW, but was the least affected of the three.
Anyways - it's subjective and doesn't affect protection. I stopped using M1 just because of the noise, not its performance as a lubricant. I don't know if the N52 is affected and, frankly, I'm not going to spend $100 on oil to find out when there are other options on the table that I know are fine.
I found Castrol 0W30 to be substantially quieter in my M52 than Mobil1 0W40. GC is also more shear stable (doesn't thin as much). M1 0W40 starts thicker than GC but is thinner after only 6000km (4k mi).
In the last couple of years with my M52 I was running Rotella T 15W40 in the summer (super quiet, and great lab results). I started running Rotella T6 5W40 year round - not quite as quiet but was a 5W syn oil (albeit group III) so was more suitable to my climate. I was about to do an oil change and send the T6 to the lab when my E39 was totaled.
Synthetic really wasn't necessary in the M52 unless you were trying to do BMW's super long intervals or you lived in an extreme cold climate. You just need to make sure to change it "often enough", which lab analysis can help with. As I wrote in a previous post, finding a cold weather oil that is still ACEA A3 is very difficult, and GC and M1 0W40 are the best choices for that situation. Conventional oils are much better now than they were 10 years ago and the M52, M54, M62 series of engines were really easy on oil and, despite having VANOS, weren't cranky about running very specific viscosities.
Now DI cars eat oil for breakfast in North America because of the richer operating tune. There's nothing more damaging to engine oil than fuel contamination (fuel is a solvent) and in North American trim DI engines usually dump fuel into the oil. There are lab results for an Audi S4, I believe, with DI that nukes it's oil in only 1,000km. The BMW factory intervals are particularly horrifying in light of that. Without careful lab analysis, I'd probably run synthetic in any of the DI turbo cars (N54, N55) and probably change 2-3x as often as the BMW interval (if it were mine)