My introduction and query about my '61 Apache

[Apache1309]

Thanks, Ill be checking the intake gasket for sure.
I do have an oil change question however... I have read that it would be advisable to use an oil with zinc in it or cause damage to the engine. So I was just curious if anyone had reccomendations (weight, type or otherwise) for an inline 6 out in a '61 Apache with no oil filter. Also, because there is no filter, is it really just as simple and draining and refilling with 5 qts?