Piston Ring, Engine

Ring End Gap
Compression (top, gauge diameter)a 0.100-0.250 mm (0.0039-0.0098 inch)
Compression (bottom, gauge diameter) 0.27-0.42 mm (0.0106-0.0165 inch)
Oil ring (steel rail, gauge diameter) 0.15-0.65 mm(0.0059-0.0255 inch)
Max compression (top, service limit) 0.50 mm (0.0196 inch)
Max compression (bottom, service limit) 0.65 mm (0.0255 inch)
Oil ring (steel rail, service limit) 0.90 mm (0.0354 inch) max

Ring Groove Width
Compression (top) 1.230-1.245 mm (0.0484-0.0490 inch)
Compression (bottom) 1.530-1.545 mm (0.0602-0.0608 inch)
Oil ring 3.030-3.055 mm (0.1192-0.0120 inch)