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 solutionOil cooler / oil cooler hose inspection and
cleaning
Refer to “exterior parts removal and installation” in section 9d .
Oil cooler hose inspection
Inspect the oil cooler hoses for any damage and oil
leakage. If any defects are found, replace the oil cooler
hose with a new one.
Oil cooler inspection
Remove the oil cooler guard (1).
...
Clutch removal
Drain engine oil. Refer to “engine oil and filter replacement” in
section 0b .
Lift and support the fuel tank with the prop stay.
Refer to “fuel tank removal and installation” in section 1g .
Disconnect the ckp sensor coupler (1).
Remove the clutch cover (2).
...
DTC “c11” (p0340): cmp sensor circuit
malfunction
Detected condition and possible cause
Detected condition
Possible cause
The signal does not reach ecm for 3 sec. Or more, after
receiving the starter signal.
Cmp sensor circuit open or short.
Cmp sensor malfunction.
Ecm malfunction.
...