What is the required oil weight for 2000 Yamaha grizzly 600 4x4?

Well according to the [http://www.yamaha-motor.com/assets/service/manuals/2000/LIT-11626-13-06_260.pdf Owners Manual] the oil you should be using is as follows:
http://www.yamaha-motor.com/assets/service/manuals/2000/LIT-11626-13-06_260.pdf Engine Oil:
0 to 30 degree's / use SAE 5W30
10 to 95 degree's / use Yamalube 4 (10W30) or SAE 10W30
40 to 120 degree's / use Yamalube 4 (20W40) or SAE 20W40
API Service SE, SF, SG type or higher Oil quantity:
Periodic oil Change:
1.9 L (1.7 Imp qt, 2.0 US qt)
With oil filter replacement:
2.0 L 1.8 Imp qt, 2.1 US qt)
Total amount:
2.6 L (2.3 Imp qt, 2.75 US qt) Additionally the maintenace table show's you change the oil in the first month and the 6 month mark of purchase and every 6 months there after. Final gear oil/Differential gear oil Recommended oil:
SAE 80 API GL-4 Hypoid gear oil Oil quantity:
Periodic oil Change:
0.19 L (0.17 Imp qt, 0.2 US qt)
Total amount:
0.22 L (0.19 Imp qt, 0.23 US qt) Additionally the maintenace table show's you change the gear oil in the first month of purchase and every year there after.