I use regular 20W50 motor oil as it never gets really cold over here. Not sure i'd be really concerned with the SG/CG-4 spec.
I'd like to think the cheap and nasty 10W30 would have fewer additives to reduce cost, so it should be mostly squashed dinosaurs without the fancy additives to reduce wear.
Hopefully Mike will give his advise on what oil would be suitable. If the machine was under warranty, go OEM oil, but out of warranty i really don't see a reason why the cheaper stuff won't work.
