Yep I should've known that this would come back and bite me on the bum.
Most of the industry will only use SAE-30 on most of these stationary type of engines, but yes you can use what you've put in I guess.
Actually GTX was always considered the most garbage oil made. It had huge amounts of marketing put behind it and sold by the pallet load here in Australia where the oil market was huge, but in saying that a "Better Class of Mechanic" would never use GTX with all it's friction modifiers.
I've actually still got an old 4 litre container with some old GTX here and only use it as crap spot oiling in an oil can for hinges or anything that needs some slippery stuff on it that I won't cry over it's wastage.
I now use Synthetic 30 and no more mineral oil at all in anything that I rebuild or service. Synthetics are just a far better standard of oil and that's the way most manufacturers are heading towards.
Cheers,
BB.
