Smoking Vectra - Robes

I made the mistake of buying a Vectra (1996 DOHC 16V) from an auction to fix up. I have replaced the head gasket which was blown and the cam belt and now I just want to get rid of it and cut my losses. Although it now starts up and idles ok, after driven for about 5 miles blue smoke suddenly starts to pour from the exhaust. I have left it running in the driveway for over a half an hour and although a little smoky it will not seem to replicate the road test? Any advice on a low cost cure would be appreciated.
Smoking Vectra - Grenache
Is this a diesel or petrol?

In either case, replace the air filter and use a dose of injector cleaner
Smoking Vectra - Collos25
Rings or valve stem oil seals in other words its past its sell by date, the reason it was in the auction in the first place.
Smoking Vectra - jc2
You may have a problem with oil draining back from the head to the sump which is why it does not show up at idle but only at higher speeds;I don't know where the oil drains are on this engine but if you have done work on the top end there may be some muck in them.
Smoking Vectra - Robes
its a petrol, Thanks for the suggestion, I will try what you say