I've been through this quandary over the past couple months as well. I had just switched from M1 5w-30 to GC in my MINI on the last oil change and didn't want to go back. My main concern in finding a replacement was the long OCI on the MINI. I wanted something that could go 8 or 10k miles and withstand the added temps of a supercharger running up to 15 lbs of boost. My search ended today with me ordering a case of Redline 5w-30 from JSC Speed (the cheapest I've found it). Amsoil series 2000 was also on my list but that was more than Redline.
I've seen some very good reports on BMW 5w-30. It's not your garden variety Syntec and is ACEA A3/B3. It's also decently priced as well, especially if you are doing 5k mile oil changes.
I've seen some very good reports on BMW 5w-30. It's not your garden variety Syntec and is ACEA A3/B3. It's also decently priced as well, especially if you are doing 5k mile oil changes.