Check your sticker under the hood. My SD says 2.9lbs for R12. Not sure what your car takes but you can easily do the math. Just plug in your R12 weight in place of 2.9 below.

2.9lbs x 16 oz/ 1 lb = 46.4 oz

46.4 oz x .85 = 39.44 oz

39.44 oz /12oz in 1 can = 3.29 cans

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD