Bluestream,
You have M30 engine and may use any oil except xW-20, xW-30 ACEA A1/B1, A5/B5 and pure diesel.
First you have to decide: synthetic or semi-synthetic (no mineral oil for BMW, please). Use of PAO synthetic oil now may cause seal shrinkage and therefore oil leakage. This may happen with 80 % probability and usually the rear seal of crank-shaft starts to leak first. But nothing serious: all 6 cylinders owners experienced this sooner or later despite M30 is still considered as the most reliable and succesful engine.
I am not familiar with Amsoil, Redline or Neo, so cannot give some comments. As for non exotic for me brands available on N.A. market, depending on weather and application the choice would be (in alphabetical order):
- 5W-40: Havoline Synthetic, Liqui(Lubro)Moly, Motul 6100 Synergie or its new version 8100 X-cess, Valvoline SynPower, 76 Pure Synthetic (all PAO + group III);
- 10W-40: Motul 6100 (PAO + III), 4100 (III +PAO)
- 5W-50: Castrol Syntec (mainly III + E)
- 15W-50: Mobil1 (PAO), Motul 6100 (PAO + III)
- 10W-60: Castrol TWS Motosport (PAO + E)
- 0W-40: Mobil1 (PAO+AA+E), Motul 8100 E-Tech (E + PAO)
- 0W-30: Castrol Formula SLX (PAO)
I would avoid 0W-30/0W-40 for summer and be careful with CH-4/SJ oil use in high revving engines due to high ash content. No way for CI-4/SL where the ash content may be even higher.
My personal choice for M30: 1. Castrol TWS 10W-60, 2. Mobil1 15W-50, 3. Castrol Syntec 5W-50.
And don't worry about spread and engine cleanliness: with any of a.m. oils the engine will be clean more then enough. Just follow
recommended 7.500 km or 2 times a year drain
intervals.
To make a compromise you can use
If it is not a problem and you are are more interested to engine protection