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.
Engineers said the cost of SkyActiv technology is no more than conventional cars, too. The Mazda 3 will get a 2.0-liter SkyActiv gasoline engine this fall, perhaps as early as October. The new Mazda CX-5 will get it next, in early 2012. Look for SkyActiv-D diesel engines in late 2012 or early 2013. And that's not all.