It really comes down to the roll vs slide ratio with gearing. Too much sliding and you need a GL5. Just worked through this when working with an oil manufacturer for a transaxle im designing. Next those gear sets might also be spiral bevels, not hypoids like the oil suggests. Different tooth...
Interestingly the viscosity on my 2017 N55 X5 after 4100 miles was almost identical. I’ll have another UOA of the X5 in a few weeks with 6000+ on it to share. I wonder if BMW intended this oil to drop viscosity down into the high 8s/low 9s after running in a little.
I think 31 session, 15 minutes each. Oil temps seem to stabilize around 220F in sessions with traffic. Peaking around 230F if I can hot lap with minimal traffic. Looking at my fuel logs… 521 miles on track is what I estimate.
I think that’s perfectly fine given driving style and knowing that the N55 M2 motor has iron cylinder liners instead of the normal N55 coated aluminum.
I certainly have, but the car was validated on this oil so I wanted to see how it performed before making changes. It seems like the factory oil is doing fine based on this report.
Higher viscosity would reduce engine efficiency, which would reduce power and increase heat. If I were to...
9 track days. Stock powertrain with BMW genuine oil and filters. Oil temp reach a peak for 230F during track use, the cooling system is great on these cars.
I’d either run the factory fluid, or a GL-5 oil. Also remember too the differential gears see extreme pressures and may need a GL-5 unless they performed acceptably for the validated factory fluid.
Unless this is for a transaxle. The GL-4 because of the Syncro material
I spoke with someone at my work who specializes in torque vectoring axles and wet clutches. He mentioned that OEM's are usually quite picky with the friction modifier formulations and concentrations for wet clutches. I'm sure this BG Syncroshift MTF does not meet whatever the TF0780 spec is. I...
I’m sure majority of those requirements revolve around the slipperiness and quality of additives so it does not break down quickly with heat (towing/aggressive driving) and the wet clutch friction characteristics are as designed.
Good information here. The service manager I spoke to stated he’s been there 13 years and they like to change the drivetrain fluids at 50k to prevent future problems and failures. I assume he’s seen thousands of BMWs come through and hundreds get this service. I assume if it was a problem they...