Up to 60,000 car owners are being urged to have their vehicles inspected before the banning of leaded petrol sales in Ireland on January 1st.
The Department of the Environment estimates that between 23,000 and 60,000 of Ireland's 1.13 million vehicles will be affected by the ban.
Leaded petrol sales have been declining and by the end of 1998 accounted for just 15 per cent of sales. The leaded ban is being implemented to comply with an EU directive aimed at combating vehicle emission pollution.
Some vehicles currently using leaded petrol will be able to switch to unleaded with a minor adjustment to the engine's ignition timing.
Other vehicles may have relatively soft valve seats which wear more rapidly if ordinary unleaded petrol is used. It may be possible to replaced these valve seats with hardened valve seats, suited to unleaded petrol use.
However, the engines of some vehicles cannot be adjusted, and these will have to use either a lead-substitute petrol or a lead-alternative additive which can be added to unleaded petrol at the pumps.
Mr Cyril McHugh, the chief executive of the Society of the Irish Motoring Industry, said the decision on whether lead-substitute fuel or lead-alternative additives would become available would be made by the major oil firms.
However, he believed only minor adjustments or tuning would be required to enable most vehicles currently running on leaded petrol to switch to unleaded fuel.
The Department of the Environment and the oil companies are planning a consultation campaign aimed at the owners of older vehicles.