use 10 w 30 or 40 does not really matter
10w30
SAE 10w30 synthetic oil.
I just called a Honda ATV dealer and asked him what oil to use in a 1982 ATC 110 he says 10w40. He says 10w40 was standard back in the 70,80's.
It's a 4 stroke. Use regular gas!
10w 40
type of oil to use in a 2007 klx 110
Check your owners manual. There will be page with recommended oil viscosities.
Use some 10w-40 ATV or motorcycle oil designed for wet clutch engines.
You can use 10 W 30 JASO MA or MA2 approved oil, also SAE SF or SG oil. If the engine is worn use grade 15-40.
Drain the old and add the new...use SAE 10-40
You can use any kind of 10w-40 oil for a nighthawk
Baby oil