cmcgairty Report post Posted July 1, 2009 Just purchased a used RV with a Onan Emerald 7000 generator with just over 2,000 hours. I don't know the type or grade of oil previously used. Any recommendations? Also, thoughts on regular oil vereses synthetic. Share this post Link to post Share on other sites
traderdude04@yahoo.com Report post Posted July 6, 2009 We use Synthetic 10w-40 in our Onan 5500 because of the high heat of these air cooled engines. Share this post Link to post Share on other sites
