I have a Generac Gaurdian 17k portable with 200 hrs and been using M1 HM 10w30 Syn yr-round here in the deep south.
But would Generac Syn 10w30 be any better at all?
Or would a straight 30w be better for the high heat here?
I would think the Mobil is one of the best choices for the price.
Many(most?) synthetic 10w-30 oils don't use VII's so they are a great choice. The base oil is what gives it a 10w rating. I don't think I've ever seen a SAE30 synthetic because of this property of synthetics.
I have a stationary Generac 17 kw generator that is hard wired to my house. The manual calls for 5W-30. Temps can get down into the 20's in the winter and 90's in the summer here although I have never had it kick on during the summer months other than as part of the self-testing program that is does. I use Castrol 5W-30 Magnatech full synthetic that I found on sale for about $17 for a jug.
What weight does your manual call for for a portable unit ?
typical group III fake synthetic 10-30 is a good choice, BUT real synthetic PAO + Ester oils advertised as a 30W meet the 10-30 spec WITHOUT any viscosity improvers, but since cost is about triple + its overkill as well it matters not
A friend is a Generac tech and he told me the instructor at the gen school advised using M1 5-30. He has a lot of customers that he services their Generac gens and he uses M1 5-30. Even though those generators are problem heavy, he has never had an issue with the internals of the engine.