Hey Freydaddy
I have a 1961 235 in my 52 pickup, I don't know how many miles are on the engine but when I bought it 2 1/2 years ago I changed the oil in it right away. I have been running 10w-40 in it since then. Granted I've only put about 1,000 miles on it, its under restoration projects quit a bit, but I have no oil leaks at all. May be luck but so far so good.
Good luck
