Reubs wrote:
From my experience, if a Sierra has 240 000km on the odometer and you don't notice any smoke when you drive it, then it's probably had the motor reconditioned/replaced anyway. As Zukmeister said, the odometer reading means next to stuff all.
Mine had 280,000 when I bought it - no smoke at all but did notice a drip of fresh radiator fluid on the bumper (ie he'd filled it up just before I arrived). Sure enough blew the head gasket at 295,000km so did a full rebuild - but rings etc were all still fine and had good compression, so could have got away with just a head gasket.
Owner lived about 100km from his work though so it didn't do a lot of idling or cold starts.
BTW I'd recommend buying another second hander or upgrading to a 1.6L if you do anything. Don't rebuild your current one. I spent about $2k on mine by the time I was finished (new everything, head skimmed, new clutch, flywheel machined, carby rebuild, etc) and while it runs great I now regret not putting that money into rebuilding a 1.6.....