It's amazing the b.s. that's common knowledge on the web.
1. CAFE and the required testing drove the move to thinner oils.
2. ZDDP was re-spec'ed to no more than 0.01 by the manufacturers
becuase they couldn't devise a test to quantify catalytic con-
verter poisoning or life when ZDDP was used in the oil. Hence
the move to roller lifter camshafts.
3. The move to tighter tolerances was cited as creating the need
for thinner oils. My 1956 Chrysler was built with main bear-
ing clearence to be: 0.001" to 0.0015". So why didn't Chrysler
spec 20 weight oil in 1956.
p.s. CAFE is Corporate Average Fuel Efficiency.
1. CAFE and the required testing drove the move to thinner oils.
2. ZDDP was re-spec'ed to no more than 0.01 by the manufacturers
becuase they couldn't devise a test to quantify catalytic con-
verter poisoning or life when ZDDP was used in the oil. Hence
the move to roller lifter camshafts.
3. The move to tighter tolerances was cited as creating the need
for thinner oils. My 1956 Chrysler was built with main bear-
ing clearence to be: 0.001" to 0.0015". So why didn't Chrysler
spec 20 weight oil in 1956.
p.s. CAFE is Corporate Average Fuel Efficiency.
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