Hi All, I just purchased a 1999 Yamaha YZ400F used. I also purchased the service manual. The service manual says to use a 10w-30 or 10w-40 type oil. Is this ok to use or is there something better I should use. I changed the oil when I bought it and havent ridden it yet. I put 10w-40 in it. I just wanted to check with you all before I go riding and do any damage. I appreciate any help you could give me. This is my first 4 stroke, My last bike was a 1983 YZ490 2 stroke and there is alot to get used to. Thanks everyone!.