Can I use the cheap tcw3 marine oil

[weedeater]

i was told by a mech that he only runs o.p. oil in his motor and he runs a hopped up 250 merc on a bullet. i am runnin a 25 yammy and i was askin him about the oil i run which is amsoil and he said it was really good stuff if you want to spend the money which he then told me again about his o.p. oil, so i finally ask him about this o.p. oil to be told that it stands for other peoples oil. he told me when he removes oil systems from outboards he just keeps the oil out of the tank if people dont want it and mixes it in his gas.