oil type, weight, and filter???

[beccagz250]

i am going to be doing a service on my gz that i just bought, and was wondering if a motorcycle specific oil is needed for the engine, or if just regular old 10w40 that you buy at the store for cars is ok?? also, any preferences with brands, or using a weight other than 10w40? also is there a cross reference number for a purolator or other aftermarket filter that can be used on the bike that i may be able to find at the local parts store, instead of overpaying at the dealer??

any input with your opinion on this matter would be greatly appreciated.