A friend of mine just had his engine rebuilt in his '54 Chevy BelAir(?) 4 door. I don't know much about american cars. In his original owners handbook, I spotted an oil recommendation for straight 20 grade oil for the current temperature climate we are in. I know modern cars use light oil for their very tight clearances but did Chevy have a good reason for a light oil or was it just for fuel economy or to help prevent the owner of the car driving far north to discover when he next starts the car that he forgot to switch to a lighter viscosity? The place who rebuilt the engine used a new cam, and filled it with straight 30 non detergent. Hopefully they used a splash of zinc or similar break-in lubricant. I suggested that my friend should consider Valvoline VR1 10w30, but I figured I should ask on here about the straight oil recommendation on the owners manual. What are your thoughts?
