This is another question for a friends car. I am going through the car, checking the brakes and changing the fluids.

Per the FSM and owner's manual the rear diff takes 90W gear oil, unless it's a limited slip differental. In that case it requires a "special hypoid oil"

How does one tell which diff. the car has. The car is a 1974 450SL

I will add that when playing around with the brakes on the back end, I found that I was able to rotate one wheel, with the other on the ground. this of course leads me to suspect it has a limited slip diff. If I am correct, what is, and more important, where can I get this "special oil"

Thank you again.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member