Checking Side Clearance of Top Ring
This is all you have to do, to check if the Piston &
Cylinders need replacing. 
With the top ring compressed in it's grove, place the thickest
feeler
gage that will fit in the grove along side the ring.
VW lists maximum side clearance of the top ring as .0495
We
tell our customers if the ring side clearance is over .005/.006"
then it's a
waste of time and money installing new rings.
The VW Cylinders are very
hard and if you see a ring grove in
the cylinder then it's most certain
past time to replace the P&C.