We have a jerrycan of 20W50 laying around which is specifically made for classic cars. We use it all the time for our MG B (inline 4) and it always runs great. But that's why I asked what kind of oil I should use for our truck, because I don't know if 20W50 is a good oil for it. Getting the oil is no issue, because we have a couple of jerrycans laying around with 15W40 but I don't know how much zinc is in it.
