My Benz is a 560SL with 153K on the clock. The owner's manual specifies up to 20W50 for warm weather (down to about 32F minimum, IIRC). I use it, in the form of Valvoline's high-mileage-engine dino formula. Consumption is modest; I change every 3000 miles and find it's probably down about a quart when it's time to change. Consumption was notably higher with 10W30, which in my engine isn't recommended for summer conditions.

I'd start by looking to your manual for viscosity recommendations, then making your c