Expire is not really the right term; but effectively yes. In general a cheque older than six months will be considered stale-dated and will not be honoured. Reference the Canadian Payments Association FAQ.
SKYACTIV is a brand name for a series of technologies developed by Mazda which increase fuel efficiency and engine output. The initial announcement of the SKYACTIV technologies include new engines, transmissions, body, and chassis, which appeared in Mazda products from 2011.
Toyota's makeover comes as rivals such as Honda Motor Co. and Mazda Motor Corp. overhaul their engine lineups to meet increasingly stringent fuel economy regulations. Honda's line of Earth Dreams engines taps direct injection technology and turbocharging. Mazda's Skyactiv engines pair fuel injection with high compression ratios. Toyota's first TNGA cars, complete with new platforms, are due in 2015. But the first of the fresh engines debuted in April in the Toyota Passo, a Japan-market hatchback.