Car blowing blue smoke, possible valve stem seals?

Worn stem seals characteristically give some smoke after the car has been idling for a while, say, at the traffic lights. If you have continual smoke, check your crankcase breather system &/or do a compression check for worn piston rings/bores.

The sure-fire test for valve stem seals is that with the throttle open, driving along, no smoke.
Shut the throttle with the engine revving, ie slowing for a corner, then the piston going down will try to suck oil down the valve guides, if possible. Go round the corner and drive out from the apex - as soon as the throttle opens, poof a delicate little puff of blue then no more. That's your worn guides and/or seals.
Best seen by buddy in the car behind.
 Now smoke at idle, I guess it could be guides, or rings, or something else....
Rings blow smoke under power, say driving up a hill ...constantly (until you run out of oil).