[SlowToady]

I don't know anything about cleaning a cat, but...

What model year is the Jetta? There is a KNOWN issue that VW has issued a TSB for, that address the fact that piston rings on 2.0L engines were installed UPSIDE DOWN at the factory, and this causes excess oil consumption, about 1 quart every 1000 miles; that is PFH for a 105HP 2.0L I4. Note that my 2001 Golf with the 2.0 uses....1qt/1000mi. If the vehicle is under warranty, you should take it to the dealer with a copy of the TSB and complain until they fix it. If you don't say anything, they won't, because replacing piston rings @dealer labor rate is NOT inexpensive. I don't recall the TSB number off the top of my head, but you can find it on VWVortex.com.

The oil consumption is particularity bothersome to me because I run Mobil 1. At $6/qt, I don't want it burning anything! Apparently the dealer "forgot" to mention that TSB to me, and I'm long past the warranty coverage. I have no plans to fix it, and will just drive it until it gives up the ghost. It's just shy of 100K, so that might not be too much longer:-P

Good luck...