Do you know what year of manufacture the engine is. Reason I asked is that I believe Olds stopped building their Olds engines in the late 70's/early 80's. They went to using engines by GM due to lawsuit . Story was that somebody bought an Oldsmobile that was advertised to have an Olds engine in it, and it turned out to be a standard GM engine. Guy (class action???) sued for false advertising, so Oldsmobile stopped advertising their engines as being Oldsmobile engines. Olds still had different cube sizes as well as the other GM brands, but many parts were GM.

At least that I was told by my Olds people. Could be they lied about it, but I couldn't detect it.