My Nissan sunny FB14 fitted with GA15DE engine is smoking intermittently and consumption of oil has gone up. I consulted a mechanic who observed it and said it could be that the VALVE SEALS are worn out which are allowing seepage of oil.
He also said that there was need to replace the valve seals.
He told me that instead of just replacing the valve seals, its advisable to buy overhaul gasket set and piston rings so that all these are replaced.
My question is that is it necessary to overhaul the engine when only the seals are worn?
What are the implications if we just do a top overhaul?
Replacing the valve seals should at least reduce the oil consumption by 70 % and it can be attained by not removing the cylinder head. If you are going to remove the cylinder head to do the job, I would recommend replacing the piston rings as well as you are already more than half way there. This would help in reducing the oil consumption caused by worn oil rings and also help in increasing compression due to worn piston compression rings.