Unleaded fuel — do you need the additive?

Ruapehu Bulletin, Volume 13, Issue 624, 20 February 1996, Page 6

Unleaded fuel — do you need the additive?

In January premium unleaded 96 octane fuel became available at petrol stations. This ehange does not affect owners of newer cars but will impact considerably on owners of older cars. The latter will be required to use an additive to protect their cars from valve seat recession. Garages have booklets or tables that identify each make and model of car, type of petrol they require — unleaded 91 or 96 — and whether they require the additive. As a guide, the following cars will not need to use the additive: Japanese cars built since 1 98 1 ; Any car sold new in NZ since 1985; Second hand Japanese imports; CNG/ LPG converted cars (with hardened inserts). All other cars will either: need to use the additive at all times; or be recommended to do so especially when towing or at speed. In the case of your lawnmower, tractor, motorcycle and outboard motor it is advisable to contact the manufacturer of any engine which used leaded gasoline. If this proves too difficult it is recommended that any 4-stroke engine made before 1986 be run with an additive as a safeguard. If the appliance is 2-stroke, no additive is needed as generally mechanical exhaust valves are not used. New Zealand is one of the last countries in the Western World to convert to unleaded super. There is no doubt that lead is a poison and we were overdue to clean up our exhaust emissions, say most people, especially considering New Zealand' s supposed clean, green image. As of December 31,1 995 it is illegal for any leaded fuel to be imported into New Zealand and as of September 30, 1996 it will be illegal for any leaded fuel to be sold here. Lead was discovered to provide an octane boost to gasoline in the 1940's and this feature was first exploited for improved engines for Spitfire planes during World War 2. In the late 1980's it was found to be incompatible with catalytic converters used for pollution control. In addition to octane enhancement, lead provides a protective barrier preventing wear or recession at the engine' s valve seats. Valve Seat Recession occurs due to microscopic welding and tearing of metal from the valve seat faces. Older engines were designed to run on leaded petrol and have soft valve seats. Turn to Page 10

Unleaded fuel — do you need the additive?

FROMPAGE6 Valve seat wear or recession (VSR) occurs when older vehicles designed to use leaded gasoline are operated on unleaded gasoline. This is because lead acts as a solid lubricant between the exhaust valve and the soft exhaust valve seat, preventing the valve from recessing into the cylinder head. VSR can cause valve burning, loss of performance and if allowed to progress unchecked, will ultimately result in loss of compression and engineiailure. Additives containing phosphorous have been found to be the next most effective anti-VSR additive to lead. According to Asia Pacific Specialty Chemicals (NZ) Ltd, their product — Valvemaster — has the unanimous endorsement of the four major oil companies in New Zealand as the preferred additive. Valvemaster is a phosphorous based anti-VSR additive which has bee extensively proven in independent tests. It has had many years of successful use in North America. As the additive Valvemaster has a phosphorous base it should never be used in cars fitted with catalytic converters as in time it will deactivate the catalyst. Occasional misfueling with Valvemaster is tolerable. The switch to unleaded in New Zealand was inevitable. Europeans and Japanese define what fuel we use because they design our cars.