I believe the 75, 80, 90 weight range is preferred for most normal driving as opposed to the 85W140, which I believe is formulated for those that race or tow. There's pros and cons to each type. You don't want to use 85W140 for every application, since it has modifiers which break down faster than the base oil, plus the modifiers displace a fraction of the base oil, which is where the lubrication comes from. But you DO want to use it for extreme heat applications, such as racing or towing.

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95 E320 Cabriolet, 159K