You can download a PDF of the manual. Go to this link: »
www.searspartsdirect.com ··· 14x00001 and enter the Sears model number. It will be a xxx.xxxxx type of number and can usually be found on a sticker under the seat and/or on the bottom side of the hood. In one of the sidebar areas is where I found the link to download the manual for mine.
My LT1000 with a B&S 17.5 HP engine specs 30 weight, but like Msradell, I run 10-30 synthetic in it.