Mobil makes a 0-40 formulation of its synthetic, Mobil 1. It is the standard viscosity that many MB dealerships use. It covers a lot of temperature range, and is better suited (some feel) for V8 engines in particular, esp. those that tend to "run hot." The larger number of any multi-viscosity oil describes the ability of the oil to resist thinning out at high temperatures. The higher the number, the more heat the oil can tolerate without thinning out.

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Steve
'93 400E