My 86 300sdl has about 131,000 miles. It smokes on start up. Seems to be diesel smoke. I haven't noticed any blue or white. The only other time it smokes is if I floor it on the highway. A nice feature if someone is tailgating me. My last tank of 70% highway driving returned almost 25MPG. City driving is 22-24MPG.

BTW the valve seals were replaced by the dealer shortly before I bought the car.

Dave

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1986 300SDL