Payne recommends Ore-Lube G90/140 that is a synthetic but if you can't find that they also will use Almasol-608 quantitys for machines OA-1Qt,AA-1Qt,3A-H-2qt,B-4qt,C-6qt,D-8qt,F-13qt,300-9qt,400-12qt,500-16qt. I hope this helps