Onan p216G oil

How much oil does a Onan p216G take? I've looked at the approximate data on the documents, but I would like to hear your opinion, what consumption you get in practice, not in theory on paper. I want to buy a used Onan P216G, according to specs https://www.wersis.net/kawasaki/kws-fc540v.html it suits me perfectly, but I've never experienced this brand of engines.