My 1980 sportster calls for hd medium heavy oil
this is what i usually use, but money is tight right now and i cant afford the hd brand oil
what weight should i use if i bought another brand, like mobil 1 or castrol
some guy recomended 20w50, someone else said 5w20
what do you guys think, what is the right oil weight for a 1980 ironhead 1000?