Keyboard key legends must be extremely durable over tens of millions of depressions, since they are subjected to extreme mechanical wear from fingers and fingernails, and subject to hand oils and creams, so engraving and filling key legends with paint, as was done previously for individual switches, was never acceptable.
32.
The Puma was available with four engine options : 1.4-litre ( 1997-2000 ), 1.6-litre ( 2000-2001 ), 1.7-litre VCT ( only used in the Puma ), and the Tickford-tuned 1.7-litre VCT ( which was only used in the Ford Racing Puma ), each of which used oil ( 5W30 semisynthetic ) to minimise mechanical wear.
33.
Later in its life, after mechanical wear has increased the spacing between the piston and the cylinder ( with a consequent decrease in power output ) the cylinders may be machined to a slightly larger diameter to receive new sleeves ( where applicable ) and piston rings, a process sometimes known as " reboring ".
