M50 325 and m50 525 difference?

[Stevoyayaya3]

Merry Christmas guys. I have a question. I have a m50 in my e30. I've looked up the Bentley books for both cars. One says it takes 6.1 quarts and the other says 6.9. Also the oils you can put in are different. I run 20w50 redline and the motor feels great. My thing is what's the difference? How can I tell which motor I need or is it just the oil pans are different hence the .7-.8 quart diff? Thanks guys

[DesertBMW]

Who cares what the book says. you put 5 liters, then measure using dipstick, start the car, then turn it off. Then measure again, then add more until you are at max. 20w50 is too thick for M50.

[Kingb]

Yes 20w 50 is too thick. Run 15w40. That's what we use at the dealership 7 quarts.

[mitchlikesbikes]

isn't the difference due to the 325 m50 being a rear sump pan and the 525 m50 being a front sump pan?

but if you have the 325 one in your car that means you have the 525's oil pan anyway so it might as well be the 525 m50... right?