Classic cars need frequent oil changes due to less efficient filtration and blow-by; modern detergents can help

https://atomic-wiki.win/index.php/Same_Day_Oil_Change_Greensboro:_Beat_the_Wait_Times

Classic cars need frequent oil changes due to less efficient filtration and blow-by; modern detergents can help, but always choose an oil with appropriate zinc levels for flat-tappet cams.