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.
10w-40
.6 of a quart, same for the 50.
engine oil
1000
45+
Depends on the model. CRF 80f will go about 40 mph, a CRF 100f will go 50-55 mph, a CRF 150F will go 60-70 mph, a CRF 250 will completley depend on the terrain and rider but the top speed is about 70 or more
Stock, a CRF 150F will do around 60 mph while a CRF 150R will probably go a bit past 70 mph.
Use a chain wax, not an oil. Any kind would do just make sure not to use an corrosive materials like WD-40.
with new ones
It goes about 70-85 mph
maybe 35 to 40 mph
40 miles an hour