Oil quality is a major contributor to your engine's performance and life. Always select good quality engine oil. Suzuki recommends the use of suzuki performance 4 motor oil or equivalent engine oil. Use sf/sg or sh/ sj with jaso ma in api (american petroleum institute) classification.

Api: american petroleum institute jaso: japanese automobile standards organization
Sae engine 011 viscosity
Suzuki recommends the use of sae 1 ow-40 engine oil. If sae 10w-40 engine oil is not available, select an alternative according to the following chart.

Jaso T903
The jaso t903 standard is an index to select engine oils for 4- stroke motorcycle and atv engines. Motorcycle and atv engines lubricate clutch and transmission gears with engine oil. Jaso t903 specifies performance requ irements for motorcycle and atv clutches and transmission.
There are two classes, ma and mb. The oil container has following classification for confirming the standard.

Energy conserving
Suzuki does not recommend the use of "energy conserving" oi ls. Some engine oils which is api sh or greater has "energy conserving" indication in api classification doughnut mark.
These oils can affect engine life and clutch performance.
Fuel
Engine coolant solutionRadiator / cooling fan motor removal and
installation
Removal
Remove the inner under cowlings. Refer to “exterior parts removal and
installation” in section 9d .
Drain engine coolant. Refer to “cooling system inspection” in section
0b .
Disconnect the reservoir tank inlet hose (1) and
water air bleed hose (2).
Remove ...
Oil pump inspection
Inspect the oil pump in the following procedures:
remove the oil pump. Refer to “oil pump removal and installation” .
Rotate the oil pump by hand and check that it moves
smoothly. If it does not move smoothly, replace the
oil pump assembly.
Caution
do not attempt t ...
Brake system inspection
Inspect brake system
initially at 1 000 km (600 miles, 2 months) and every
6 000 km (4 000 miles, 12 months) thereafter
Inspect brake hose and brake fluid
every 6 000 km (4 000 miles, 12 months)
The brake system of this motorcycle is
filled with a glycol-based brake flui ...