Just got the m3 and need to do oil change and rear end gear lube. I will be driving this car eveyday in Connecticut winters. Can I drop down fron 20-50 to say 10-30? I plan to use synthetic only if this will make a difference in viscosity choice.
what is the normal viscosity choice for rear end and how do I determine the correct level? I am getting a shop manual but need help now.
Finally, I am experiencing some oil loss between changes. Approximately 1 quart to 1.5 quarts depending on the hammer it factor.