synthetic oil for onan generator
I've looked at past posts and there seems to be many being that recommend using synthetic oil in the generator. I have an onan 5500 lp generator and it's time to change the oil. based upon the temperatures where we live (below freezing to over 100) the recommendation is to use 15w-40 oil. so I tried to find a brand of synthetic oil in this viscosity. I couldn't find any. all the ones that are 15w-40 are for cj service (diesel engines). so my question is what are people using? (brand, viscosity, gas or diesel, and is what they are using the same as what is recommended?