273 rocker arm adjustment

Ran 20-50 Valvoline Racing oil for 300,000 miles in the 67 Barracuda with a 273 and 200,000 miles in a 64 4 speed Barracuda HP 273. Daily drivers and had no oiling problems at all. Lived 5 years in South Dakota and years in Florida and more than a few places in between. 20-50 is not a problem.