An Old Rover Group Memo

[21jigsaw]

END OF THE ROAD FOR LEADED PETROL

The European Union will ban leaded petrol (4 star) from 1st January 2000, apart from a very small amount allowed to be sold for classic vehicles. It is not yet clear just how that small amount will be distributed, and it has to be assumed that most filling stations will no longer stock leaded petrol from 2000. There will, however, be Lead Replacement Petrol (LRP) and separate replacement additives available.

Why was Lead needed?

Lead in petrol had two main functions. The first was to increase the octane number of the petrol (preventing the mixture igniting too soon) and the other was to lubricate valve seats to reduce wear from the action of the valves hammering against the seat.

All recent cars (certainly since 1992, and many before that) have to be capable of running on unleaded petrol as the lead poisons exhaust emission control catalysts. These cars have hardened valve seats to avoid the need for lead, and are fitted with a narrow filler neck so that 4 star petrol cannot be used. Although catalyst cars must use unleaded, you do not need to have a catalyst fitted to use unleaded or Lead Replacement Petrol.

Many cars built between the mid 1980s and 1992 can run on either leaded or unleaded. These cars all have hardened valve seats but do not have the narrow filler neck, so either fuel can be used. Some may need re-tuning to use the normal Premium (BS EN228) unleaded fuel, which is 95 octane rather than the 97 of 4 star (BS4040), or they can use “Super” unleaded (BS7800) which is 98 octane. If the owners’ manual says the car is capable of running on “either 4 star or unleaded”, it will have hardened valve seats and so does not need lead for lubrication.

Valve Seat Recession

Many older vehicles and some from even the late 1980s have ‘soft’ valve seats and so need the lead to control valve seat recession.

There is a “memory” effect from the past use of lead. This was why some manufacturers offered “unleaded-capable” cars that actually needed one tank of 4 star petrol to every two or three of unleaded. These cars had soft seats and needed to use this “memory” effect. The length of time that this memory will last is uncertain, though, and should not be relied upon to give adequate protection once leaded petrol is withdrawn from sale.

The amount of wear that occurs depends on the driving conditions, and particularly the resulting valve seat temperatures. Under very mild driving conditions, little or no wear may occur even with soft seats on unleaded petrol; but under harder driving conditions such as continuous motorway speeds and/or towing, recession can be fairly rapid. Whilst rebuilding and regrinding valve seats may have been a regular job in the past, it is unlikely that many motorists today would wish to undertake that task – even on classic vehicles where it was originally part of the joys of motoring!

For these vehicles there are two main options – either to fit hardened seats (this may involve replacing the cylinder head), or to use a Lead Replacement Petrol. Fitting hardened seats is not, unfortunately, a low cost option. It is generally more difficult on those engines with cast iron heads and a cast-in seat than on alloy heads that usually already have a seat insert, albeit a ‘soft’ one. The new seats need to be made from a material that will match the hardness of the valve, otherwise the wear pattern could be reversed, with the new hardened seat wearing out the valve.

Lead Replacement Petrol

Lead Replacement Petrol (LRP) is a comparatively new option for the U.K. This type of petrol uses other additives – typically based on potassium, phosphorus or manganese – to give valve seat wear protection. It is now widely believed that they do not give as high a level of protection as lead, particularly under more arduous duty, but they will certainly give a much greater degree of protection than unleaded petrol, and should be adequate for “normal” use when leaded petrol is no longer available.

The British Standards Institution (BSI) is developing a specification for LRP. This will be a 97 octane petrol (like 4 star) with controlled amounts of an additive. It will be dispensed through pumps with wide nozzles (like 4 star), and the pump labelling colour is expected to remain red, with 4 stars. The new standard should be available well before 4 star is removed from sale but a BS number has not yet been allocated to it. There is no firm information yet from the oil industry as to how many filling stations are likely to sell it after 2000, but as 4 star still has a significant market share it is expected that most companies will offer LRP. This type of product is already available from some of the filling stations of at least one company.

After-market Additives

It is also likely that these alternative types of additive will be made available as after-market treatments, so that the motorist can buy a can of additive to add to a tankful of unleaded petrol. In this case it is important to use only the recommended dosage, and to ensure that the product is designed to protect from valve seat recession, not simply an octane booster. Sodium-based additives cannot currently be recommended by Rover Group for cars with turbochargers, and mixing ‘active ingredients’ is not recommended.

There is no British Standard for separate additives.

Outside the U.K.

Although the ban on leaded petrol is an EU directive, member states can apply for a delay if they demonstrate economic hardship. Some countries may thus still have some leaded petrol available in decreasing amounts, but most will not. Indeed it is already disappearing from some countries, notably Germany, Sweden and Austria.

The availability of alternatives varies from country to country. LRP equivalents are used in several of the Scandinavian countries, but sale of petrol with any metallic replacement additives is prohibited in Germany, so many filling stations sell the after-market treatments for the customer to use. In Austria, on the other hand, all “Super” (98 octane) unleaded petrol has to have lead replacement additives.

If you wish to take a car needing leaded petrol to other countries, it is therefore wise to check local availability first, or at least take a supply of additives with you!

Summary

Leaded Petrol (4 star) will be withdrawn from 1 January 2000.
Many cars can run on unleaded without modification or with re-tuning.
Cars with ‘soft’ valve seats needed lead to control recession.
A catalyst is not needed to use unleaded.
For ‘soft’ seats, the main options are new seats or lead replacement additives.
Lead Replacement Petrol will be available.
After-market additives are likely to be available – check they’re the right kind.
Options will vary from country to country.

[Toughie]

The way I drive, I doubt I'll still be alive on 1st January 2000, so shalln't worry about it!