Cruising Sailors Forum Archive
I found my own answer
In Response To: Also, I assume you're changing the oil -- not just adding some synthetic to the regular oil (or vice versa)? 
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() Apparently the Rotella is a Group III (3) synthetic, as per this page. See link http://www.upmpg.com/tech_articles/motoroil_viscosity/
Toward the bottom they answer my question. Will return it and use 15w-40.
