Owners of old vehicles which run on LRP, lead replacement petrol, will be in for some additional costs this year because from the beginning of next year, LRP will no longer be available for retail, and adjustments will have to be made to vehicles.

Enemalta said yesterday that newer EU fuel quality directives which will come into force on 1 January will affect the current composition of LRP fuel by reducing the metallic to a third of what is currently present in LRP.

The reduction in Metallic Manganese additives will affect the performance of LRP in two ways: there will be a reduction in the octane number, and a reduction in exhaust valve seat protection.

Enemalta said the reduction in octane number might induce engine-knock and the simplest remedy for this might be to have the spark-timing retarded and adjusted by a professional motor technician/mechanic. If this is not enough, an ‘octane booster’, bought over the counter from petrol stations, would have to be added to the unleaded petrol.

The valve seat protection can be dealt with in different ways. The simplest and cheapest solution, Enemalta said, is to purchase unleaded petrol and add a suitable fuel additive that protects the exhaust valve seat from excessive wear. Another solution is to replace the existing exhaust valve seat to a hardened one although this option is more costly, but might be worthwhile, especially if the engine is being reconditioned, the cylinder head is being removed for other mechanical maintenance, or the car is kept as a classic.

Enemalta’s advice to owners of vehicles which run on LRP is to seek the advice of a professional motor technician/mechanic to check if their vehicle is suitable to run on unleaded petrol. If not, they would be advised on what modifications and/or adjustments might be necessary to make such a changeover.