Worn cylinder walls

I have an very old engine with worn cylinder walls. I need the engine to survive a bit longer so am not looking to run out and spend loads of money on. The escaping air/diesel/exhaust fumes are getting into the sump, creating pressure and forcing oil out. Without pulling the engine out and reconditioning it I'm looking for something to add to the oil or coat the cylinder walls with to create a snugger fit for the pistons.

Thanks

Fizz the ferret

Lucas Heavy Duty Oil Stabalizer will help matters. I've seen it massively reducing the burning of oil in several cars - it actually works unlike the similar Wynns and STP products.