10w40 oil if you are using a non-Honda oil. We just switched our crf's (2 of them) to Amsoil and I can honestly say we felt a difference in the first 5 minutes!
A Honda CRF-50 uses a 10w30 four stroke motorcycle oil. You should not use a truck or car oil in the CRF-50.
5wt oil. Use Honda oil.
API SM oil is the kind of oil that a Honda CRF150f should use. Make sure the SM oil is either 10W-40 or 10W-30.
10w-40
about a liter
10w30 four stroke motorcycle oil. do not use car or truck oil!
10w30 is a good choice year round. I highly recommend you use synthetic oil in this air cooled engine.
Regular unleaded is fine. It's a 4stroke so you don't need to add oil.
i got a 2003 model i gave it an oil change and advised to use 10w/40 synthetic.
always use four stroke motorcycle oil. valvoline, castrol, Honda etc. I use 10 w 40. 20 w 50 is a little too thick unless your motor is worn out. NEVER use oil for cars and trucks.
Honda recommends 92 octane at least for this bike.
A CRF 70 will use 10 W 40 with a MA rating. The oil must be approved for motorcycle use. This oil can be found at auto parts stores and also at bike stores.