Changed the oil in the 77 300d and 85 300td today. Used same process on both. Added 6 qts to each, let run for 2 min. and then checked the oil to top it off. 77's oil was as black as usual after 2 min and the 85's was still clear. Why the difference? Differrences in how the oil cooler oil gets mixed in? But if the thermostat on 77 oil cooler was stuck open, wouldn't the oil have drained out of the cooler during the change?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13