I use AMSOIL: 10w-40, 20w-50, and SAE-60, or MOBILE 1 10W-40, and 15w-50 !

AMX, GMC,T/A, and MACK get the SAE-60. . .
the Dodge and Chevy get AMSOIL 10w-40 in winter and 20w-50 in summer. . .

The Ford get's the mobile 1 10w-40 in winter 15w-50 in summer. .

Mike


1962 GMC K3000, GMC-379 V6.