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 solutionEngine stop switch inspection
Inspect the engine stop switch in the following
procedures:
turn the ignition switch off.
Remove the air cleaner box. Refer to “air cleaner box removal and
installation” in section 1d .
Disconnect the right handlebar switch coupler (1).
Inspect the engine stop ...
Cylinder inspection
Refer to “engine top side disassembly” .
Refer to “engine top side assembly” .
Cylinder distortion
Check the gasket surface of the cylinder for distortion.
Use a straightedge and thickness gauge. Take clearance
readings at several places. If any reading exceeds the
service limit, replace t ...
Fuel discharge amount inspection
Keep away from fire or spark.
Spilled gasoline should be wiped off
immediately.
Work in a well-ventilated area.
Inspect the fuel discharge amount in the following
procedures:
lift and support the fuel tank. Refer to “fuel tank remo ...