Keywords
Citation
(1999), "Lead replacement gasoline", Industrial Lubrication and Tribology, Vol. 51 No. 1. https://doi.org/10.1108/ilt.1999.01851aaa.002
Publisher
:Emerald Group Publishing Limited
Copyright © 1999, MCB UP Limited
Lead replacement gasoline
Lead replacement gasoline
Keyword Gasoline
As the date for the phasing out of leaded gasoline draws nearer (1 January 2000), more and more products are appearing on the market which claim to be able to overcome the problem of valve seat recession (VSR). Heavy wear of the exhaust valve seat may be experienced when changing from leaded to unleaded gasoline in the case of vehicles fitted with soft cast iron valve seats due to the absence of the lubricating effect of the leaded additives. Most cars built before the mid-1980s and many built prior to 1990 were designed to operate on leaded gasoline. More modern cars are fitted with hardened steel valve seats where VSR is not a problem when using unleaded gasoline. However, at 1 January 2000, there will still be a substantial vehicle population which will require valve seat protection, and there are two different approaches in providing such protection without the substantial expense of replacing valve seats. Lead-free alternatives to the leaded additives, based on sodium, potassium or phosphorus chemistries, have been developed which are claimed to provide equivalent protection. These additives may be blended into gasoline at suitable blending terminals in much the same way as other additives, e.g. detergents, are currently added. Also, they may be made available as after-market additives in packed form for the motorist to add to the tank at the time of filling. However, there have been a number of well-publicised incidents where motorists have experienced severe engine damage when changing from leaded to lead replacement gasoline, which can only cast doubts on the efficacy of at least some of these additive systems. It is high time that a suitable test procedure was established, together with appropriate internationally-agreed specifications, and the BSI are currently involved in a necessary work programme to develop such a standard. However, it is surprising in view of the many parallels with diesel fuel lubricity and its attendant problems that a suitable standard is not only currently unavailable but is also unlikely to be finalised for some time.