Brake fluid is also said to help free sticking rings.

Havn't tried it, but I've found it pretty good as a carb cleaner, so I'd say there might be something in it.

Worn or sticking piston rings.?Remove the spark plugs and put a small amount of Redex down the bores and leave for 48 hrs.(spark plugs left out).

That would be my fist move as well. Stick plenty down when engine is hot, about 15ml. Before starting cover the plug holes with a rag and turn over the engine to blast out the red-X. If you need the car every day just leave it overnight but do it twice. A healthy dolop in the fuel to will help. Will smoke a lot on start up.