i changed my diff oil and i noticed it was very dark grey is that normal??
the car has 23k on it and i got it at 20k iam not sure if its been changed before.
i also noticed on the left rear spring there is a rubber thing attached to the spring is that normal??i pulled it off anyways..

 

i also changed my oil and iam useing a hemp oil filter is that oil filter ok?? its much smaller then the one that was in there

 

The factory gear oil is high moly content and looks terrible. That is how it is supposed to be.

I'm sure you are talking about the HAMP filter. Hemp is for rope, clothes or smoking.

 

Sounds like a spring rubber. They are great when you are racing NASCAR, but not good on a S2000. Good thing you removed it.

The HAMP filter (HAMP Synergy) is recommended for the S.

 

extremely normal for the diff oil to get very dark between changes. was there a lot of gunk on the magnetic drain bolt/did you clean it off?

 

The HAMP Synergy filter is fine. The OEM oil should be gray and very smelly. Hopefully you cleaned off the drain plug and put in the correct amount of fluid