I have to agree with all that deltacom says. I use shell rotella synthetic 5 w 40 in my 350 and 450. The link below may well form part of the original article you used. it was written for motorcyclists. very well written article and factual, if you have a spare 20mins read it, its worth it, bikers with mainly air cooled engines have to be very picky about their oils

http://www.calsci.com/motorcycleinfo/Oils1.html

cheers
barri

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61 Austin mini
67 Lotus 7
74 450sl
76 Cadillac 8.2l (501 ci)

some new cars

megasquirt conversion on:
djet 74 450sl http://www.mercdjetmegasquirt.britautorepair.com/
cis 76 450sl http://www.merccismegasquirt.britautorepair.com/

the best view is always from the point of no return