Smoky on start up

[spindrift]

I have a 1900 watercooled engine, which on start up always smokes a bit, not blue or white, just a bit grey but goes away after a few minuets, plus when going down hill and holding it back on the gear's, when I get to the bottom and accelerate there's a plume of blue smoke, but no effect on overall performance.
Just wondered if I'm heading for an engine rebuild,and it doesn't appear to use much oil either.
Is this normal, the engine has done 108,000 miles and is serviced regually.

[si macc]

I'm not an expert but from reading loads of posts about smokey engines it sounds a bit like worn valve stem seals. Do a search for 'valve seals' and 'over run'.