Onan Gen coolant ??

Maybe their just topping off. Although the best solution is doing a Google search for the Onan generator they have. They can then save it as a PDF on there handheld pad. That's what I do for everything. Always have it when needed and wherever we are. That's what I copied and pasted from above.

I think many people just want to do it the easiest way and ask. In my opinion you then just get a bunch of answers, some right , some wrong. Owners manual never lies.