I noticed my cas was leaking when I changed my timing belt. So I replaced that o ring with the one that came in the timing belt kit from fm. Install went fine no problems at all. Drove a couple 100 miles, checked and still oil on the bottom of the cas. I then got one of the fancy ones from miata roadster. Another couple hundred miles and it seems like that one is leaking too! What the hell is going on?

 

Perhaps you are boosting the crankcase and it's blowing past the cas o-ring?

 

Check your PCV valve.

 

I hope not! I have the gtx pcv and a check valve.

 

I managed to trash 2 CAS O-rings by installing it ham handed. It could be that you've just borked the install?

 

It's safer to remove the valve cover and loosen the CAS cap bolts.