South Africa is poised for the final phasing out of leaded petrol, eliminating lead as an air pollutant and reducing engine wear.
Catalytic converters, fitted in all new engines internationally, cannot operate on leaded petrol. To preserve its growing export potential, the local car industry fully backs the change.
The cut-off for leaded petrol manufacture is January 1 2006. By June 2006 service station petrol should contain, at worst, residual lead. Thereafter, petrol will be either unleaded or comprise lead replacement petrol (LRP), containing additives to avoid valve seat recession in old cars.
Leaded petrol has been used since the 1920s to achieve required octane numbers to prevent “knocking” — premature ignition — and engine wear. Lead additives also harden valve seats.
The new era began in the 1980s, when catalytic converters were introduced to combat pollution. As recently as 1996, one could still buy cars designed in the 1980s, so some engines still depend on lead to protect working surfaces.
From 2006 three kinds of cars will be on the road. New cars with catalytic converters will use unleaded petrol only. Most other cars can use either leaded or unleaded, and a small proportion of old cars will need LRP.
Stuart Rayner of the National Association of Automobile Manufacturers says that the organisation is preparing a public education campaign for next year.
Octane ratings will change — a major exercise. The new pricing differentials are designed to prevent wastage, as higher octane grades of lead-free petrol give a lower yield in refining. Motorists will have to consider which octane rating they need.
After the change-over, possible grades are 95 unleaded and 91 unleaded nationwide, compared with the current 93 (leaded and unleaded) inland, and 97 (leaded) and 95 (unleaded) at the coast. LRP will be available in the same octane ratings, although all variations may not be available everywhere.
The refining industry estimates about 45% of coastal cars can run on 91 octane. But the abandonment of 97 octane petrol at the coast means some vehicles will need to be retuned.
Refiners will provide higher octane inland because it is now needed by turbo-type vehicles, which correct for atmospheric pressure.
About 90% of cars will run effectively on 91 octane lead-free.
Sasol’s dual fuel will disappear along with the Blue Pump, for technical and marketing reasons.
Rayner says public concerns about the ability of old cars to run on lead-free fuel are exaggerated. Valve-seat recession has occured when very old cars were run at high speed for long periods on test beds. In practice, they are not likely to be run under such operating conditions.
LRP — which will contain additives to protect valve seats — will be available until 2010 and thereafter additives will be sold separately. Rayner estimates that, even by 2006, only about 10% of cars on the road will still need LRP, using only 5% of petrol produced.
Vehicle manufacturers want South Africa to move wholesale to the European octane rating (95 lead-free) so that all locally made models can be exported. The days of models specially designed for South Africa are over.
Rayner says price differentials matter more than export commonality. An undue price penalty in favour of 91 octane will cost the motorist and the economy more in the long-term, as manufacturers will have to introduce less fuel-efficient low octane-compatible models to satisfy consumer demand.