You are correct Spectro Primary Chain Case oil is Non-Synthetic. The recommendation to fill the primary with 18 to 20 ounces is for the purpose to prevent oil getting back into the starter. 2005 to 2011 models fill with 18 to 20 ounces in the primary. Models 2004 and earlier use 32 ounces in the primary. You are only lubricating the chain. I would want to know where the metal is coming from when you drain the primary.It's non-synthetic. Funny thing is last Friday I decided to add another 1/2 qt to my case to match the 1.5 qt capacity stamp. It made things worse. Have to slam into lower gears and much harder to get into neutral. I find this odd. 1 qt seems to work much smoother than 1.5 qts. How would 21 ounces be better? I'd thing less oil would be worse.