Finally had to add a bit of oil

[VX KAT]

When my VX was at Richard Payne.. I was told he changed the Oil to Castrol Synthetic 5W-30...
It has been like that for 15K miles... [According to Ed G., the last owner before I got it]
I hear and read lots of Mobil 1 users within the forum.. is that better than Synthetic Oil? or is Also Synthetic?

As far as the filter.. I have the OEM I believe...

Yes, it's synthetic...http://www.mobiloil.com/USA-English/.../Homepage.aspx

Even though my Amsoil has extended change intervals of 15k or 25k, I still get it changed every 3k - 5k miles. And change my PCV valve every other oil change.