273 rocker arm adjustment

20-50 is not a problem
ran it and 0-50 for years with old school clearances
however today we run tighter clearances, thinner rings, rev higher
no question that most wear is at start up (or carb choke wash)
and a 0W oil flows better cold no matter what your cold is
so I use 0W-40 most places
except on new Subaru where 0W-20 is called for
check out the new (er) VW 508 spec for 0W-20 makes all older specs obsolete
GM has service bulletins out that recommend 0W-xx instead of the OEM manuals 5W-xx
The new Corvette 0W-40 is about as good as you can get
DEXOS 2 great base stocks requied and over 900 zn and phosphorous
I'll say it again do not add ZDDP to SN oils makes EP worse
and the new VW 508 has a Calcium based EP so no ZDDP there either
It interesting that the MOBIL 1 ESP family meets
The VW 508 spec
THE VW 507 spec for the TDI turbo diesel (low particulates, low SAP)
Meets the latest MB spec for both gas and diesel
and Meets the new Corvette DEXOS 2 Spec
Made from Natural Gas
I'm going to have son switch VW TDI from the 5-30 to the 0W-40
(The 40 is a low 40 high 30 spec) he is way out of warranty but the particulate filter is pricey if you screw it up
THE ESP line is specially designed for the latest catalytic converters and sensors where additives engender expensive replacements
Not pushing Mobil- others have similar
BTW VW has been treating him royally with the emissions scandal recalls