On or around Wed, 20 Apr 2005 22:11:20 +0100, "Huw" enlightened us thusly:
actually, I reckon for an engine designed in about 1960 it was pretty advanced, and the basic design can't be that bad or it'd not have survived so long.
Bear in mind that in 1960 a car that did 100,000 miles without a rebuild was rare... and the buick/rover V8 will, if serviced regularly and properly, manage more than that before it dies.
Designers in 1960 were probably looking at an average engine life of 50,000 miles... and more to the point, average use patterns that meant that most drivers would take probably between 5 and 10 years to do that mileage.
However, doesn't alter the fact that the engine was designed originally when
20W50 was normal oil, and thinner ones were only for specialists and racers. My BMW bike engine dates from the same period and that too is only supposed to run on 20W50 - and, indeed, it doesn't like thinner stuff, quite noticeably.But the point abut temperature ranges is relevant. In this country it's rare for the ambient temp. to go over 25C, and that makes a difference to the engine operating temp. as well, or rather, to the oil temp. - in temperatures of 35+, the oil is not going to cool so well, even with an oil cooler.