I have a 8 hp snow blower,I would like to know what the oil capacity of engine and what type of motor oil i should use.What weight oil?and can you use regular sae motor oil automotive type non detergent ?

Your question as I received it did not specify the engine make, but most 8 hp Techumseh, B&S and Powermore engines take 22 to 32 oz of oil. Buy a quart, put two-thirds of the quart in the engine and check the level with the dipstick or fill hole. Add more if needed to come up to the "full" mark.
All the manufactures and Craftsman recommends 5W30 for 4 cycle winter use.
You can use regular sae oil, but I prefer to use Mobil ONE or a heavy duty oil because air cooled engines run hotter than car engines. Look for a SC/SD or greater rating on the bottle.
Change your oil once a year.
Feel free to as any other questions about your snow blower. Don't forget to rate this answer!