Hello,
I change the oil and the filter every 250 hours. I buy the oil locally. It must be 15W40 and have the API specification of CF-4 or better. It means that CG-4, CH-4, ... are OK! There are millions that obey to this!
4,5 liters are needed: about 4 liters for the engine and 0,5 liter for the gearbox. I use a simple pump and oil/fuel filter tool available at Norauto stores:
Regards, Luis