New Engine in Genset/Proper oil

[Genset]

You just gotta love all the Wannabee EXPERTS on this opinionated subject. Having been an Onan dealer for 40+ years, there is plenty horse hockey being spread around here.
What works best is when the user pays attention to the oil level, air filter condition & quality of gasoline. Using todays cheapest gasoline seems to create issues while the premo gasoline does not, its the octane thing resulting in longer storage life with out gumming up the barb jets.
As for the name brand, viscosity, synthetic etc. What ever you feel happy with, 30wt is always a good choice, but some lije other numbers. Why I say, Do what makes you happy.
Me, I would never choose a spark ignition generator, only a 1800 rpm diesel, YES I am very opinionated too, but with 40 yrs sperience.
Dave M

[mgscott4]

My Onan 5500 has a chart that shows above freezing, 30WT oil is recommended. Been using 30 WT. for 1100 hours now. Easy to change oil and filter, but a pain to slowly pour the 2 QTs of oil in without spilling. I got it figured out now.

[IdahoSRT10]

Originally Posted by navychaps

I actually was considering Royal Purple 15W40 after the "20 Hour" break in period. As I run it in my Pickup and really like it and Wally World now sells it the at a competitive price!

You almost got it! You want to use RP 10w-40 HPS. (Mobil 1 15w-40 is also good) HPS has more anti-wear properties. Allow proper cooling for your new Genset. I install a intake vent and shroud to keep the gen cooler.