| In addition to increasing the octane number, tetra ethyl lead also provides a degree of engine lubrication since lead prevents the wear of engine valve seats in vehicles manufactured with older soft-valve technology. This is an important factor in those SILAQ countries where the percentage of vehicles with soft-valve technology is high and turnover rate is low.
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| Lubrication | However, tests carried out both in the US and Europe have found that the level of lead in gasoline required for the protection of soft engine valves can be as low as 0.02-0.05 g/l. These levels are several times lower than that which is currently applied in leaded gasoline, and much lower than the permissible level under EU regulations (0.15 g/l). Furthermore, data from COWI and the results from tests carried out in Bulgaria (for Lada, Volga, and Moskvich vehicles) report the effects of unleaded gasoline on soft engine valve seats to be insignificant under normal driving conditions. Some negative effects may occur when running the engine under heavy load conditions (high RPM range), but good maintenance can prevent potential engine wear.
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| Non-lead Additives | It is also possible to replace lead with other commercially available lubricants (e.g., potassium and sodium-based additives). Engine tests carried out by the Slovnaft Refinery (in Slovakia), indicated that certain vehicle models (for example older models of Skoda) required a lubricant additive in unleaded gasoline to protect the soft engine valve seats. Similar conclusions were drawn with regard to Ladas, which tend to have a large share in car fleets in the SILAQ countries (although newer Lada models have hard exhaust valve seats and can use unleaded gasoline without problem). Moreover, some positive effects in terms of engine maintenance may, in fact, be gained by switching from leaded to unleaded gasoline with lubricating additives. Lead additives cause various problems to vehicle operation, including the build-up of deposits in the combustion chamber and on spark plugs. In order to prevent these problems, lead "scavengers" are added. Besides health concerns (emission of dioxins), the latter increase corrosion, especially in the engine's exhaust system. Therefore, there are potential costs savings on car maintenance from lead phase-out due to reduced corrosion of engines and exhaust systems. It is also believed that the removal of lead from gasoline may result in slightly improved fuel economy (as a result of engine tune-ups) and less frequent oil changes. Slovakia's experience shows there are available technological options, policy measures and alternatives in the phase-out of leaded gasoline that may be applicable in the other SILAQ countries where high vehicle age is a problem.
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| Future Targets | The efficiency of different gasoline lubricant additives requires further study, and any results obtained should be well-communicated to the public. Cost estimations should be examined along with emission data from cars, and the detrimental environmental effects. Fuel consumption and engine behavior should also be investigated. Studies are also needed with regard to the different catalytic converters available. Local action plans and administrative, economic and control regulations could accelerate this process.
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| TABLE 22: Number of Vehicles and the Need for Different Levels of RON with Lubricating Gasoline Additives (Slovakia, 1996) | ||
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| RON categorization | Number of cars | Comments |
| TYPE 1 | 419,400 (49%) | BA-91: Leaded gasoline with an Octane number of 91, including lead as the lubricating additive, with the lead content of 0.13 g/l (produced until 1994) BA-91 UNI: Lead-free gasoline with an Octane number of 91, including lubricating additive ANABEX, with the lead content of 0.005 g/l (produced since 1992). |
| TYPE 2 | 392,700 (46%) | BA-96: Lead gasoline with an Octane number of 96, including lead as the lubricating additive, with the lead content of 0.138 g/l (produced until 1993). BA 95 UNI: Lead-free gasoline with an Octane number of 95, including lubricating additive ANABEX, with the lead content of 0.004 g/l (produced since 1993). |
| TYPE 3 | 46,500 (5%) | BA 98: Leaded gasoline with an Octane number of 98, with lead as the lubricating additive, the lead content of 0.14 g/l (imported since 1994).
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