An interesting question and one I have had differing opinions on over the years.But here is a fact make of it what you will.I drained the oil from my 58 not long after I purchased it from the States perhaps I did 1500 miles and used no oil at all this was before the oil change.After the oil change I used about 1 quart in the first 300 miles .I chose to put a can of mooreys in for fear of running out before I got home and it stoped the oil use immediately .I've driven around 4000 miles with that sump full and never used a drop ,but it smells like its using oil .When I quizzed the guy in the filling station on what oil he used he said he only used the best and that was the (6 leg dog )oil don't want to use a( brand name) .I have no idea what was in it before but it sure was better than what's in it now .Take care all HOP