THE LEADED FUEL BAN IS NOW official. The UK government has finally confirmed that 4-star will be withdrawn from general sale by the end of the year. A few precious drops may still be kept available for historic racing cars; but, for the rest of us, the message from Westminster is quite clear: 'Get stuffed'. All the lobbying by classic car groups has been in vain - European law prevails.
So, do we have a genuine cause for concern? Has the issue been blown out of proportion, perhaps? This ban could affect as many as 6 million British vehicles - surely it must have been properly thought through? After all, the government says that it is aware of our fears, and has taken measures to ensure that classic motoring won't be compromised.
Hmmm... other, more reliable sources, paint a very different picture.
The Retail Motor Industry Federation (RMIF), which represents garage owners, is so worried that it recently held a seminar on the subject. Members are concerned that older engines are going to be damaged as a result of this ruling and that they, the petrol retailers, may end up shouldering the blame. In order to examine these conflicting views, we perhaps need to remind ourselves of what tetraethyl lead actually does inside an engine.
Organic lead was originally added to petrol, back in the 1920s, in order to raise its octane rating - thus allowing engines to operate efficiently, on higher compression ratios, without destructive detonation (pinking). It was then realized that the lead compounds which were deposited on valve seats acted as a protective cushion, so car makers were able to cut costs by using cheaper, softer materials. (With cast-iron heads/blocks, they usually machined the seats directly into the casting itself.) However, a tiny minority of high quality manufacturers have always used hardened valve seats.
Lead has also been shown to reduce wear on other components, such as valve guides and valve stems - even the moving parts inside fuel pumps. The coating of lead compound laid down on the valve seats and elsewhere, will remain in place for a while. This 'lead memory' accounts for the fact that some car makers say that their 'leaded-only' engines can run on a cycle of one tank leaded, three tanks unleaded. But it's unwise to rely entirely upon 'lead memory' - even under the most ideal conditions, it probably won't last more than a few thousand miles.
So the vast majority of classics require the protective qualities of leaded 4-star, and many also need its octane level (set by UK law at 97 minimum). Of course, octane levels can be raised in other ways - Super Unleaded has a rating of 98, but uses some rather unpleasant chemicals to achieve this in the absence of lead. (Indeed, the government accepts that Super Unleaded is nasty stuff, and slapped a hefty 'environmental tax' on it for that very reason.)
The protective qualities of lead can be mimicked - to some extent - by other compounds, which are blended into the 'lead replacement petrol' (LRP) that's on sale in countries that have already banned lead. These compounds (sometimes known as lead substitutes) are also sold separately, in bottled form, for adding to ordinary unleaded fuel. And, so the argument goes, the experience of countries like Sweden (which banned lead in 1992) shows that these lead substitutes are perfectly adequate.
In fact, that simply isn't true - as the RMIF seminar proved. Statistics and case studies gathered from Sweden tell a very different story. Evidence was presented to show that the most commonly used lead substitutes (sodium and potassium compounds) are not only ineffective as valve/seat/guide protectants, but - worse than that - they can actually cause severe high-temperature corrosion. In some cases, engines suffered more component damage on LRP than they would have done if they'd been running on straight unleaded!
A senior representative of the Swedish Engine Overhaulers Association stated that, post 1992, the turnover in reconditioned engines had increased by over 40%. After the lead-ban, it was noticed that engines comng in for reconditioning tended to feature extensive valve damage. Valve seat recession was evident in nearly half the engines, and valve burn damage had increased five-fold. There was also a higher incidence of valve guide/stem wear.
What is particularly significant is that engines WITH hardened valve seats were also affected. It appears that, because Super Unleaded wasn't readily available in many areas, owners of some relatively modern (pre-catalytic-converter) cars were forced to switch to lead replacement petrol simply to get the necessary octane rating. They'd previously been using leaded without any trouble - but the compounds in LRP wrecked the engines' valve seats. In other words, even the hardened seats originally fitted by the car manufacturers couldn't stand up to the corrosive effects of these lead substitutes. The problem became so acute that a new, extra hard, seat material had to be developed for use by the reconditioning companies.
The experience of the Swedish Army also provides a grim warning. Their Heglund troop carriers used Ford V6 petrol engines, with soft valve seats. No valve problems had been reported on leaded petrol, despite the fact that these heavy vehicles operate at high revs most of the time. When leaded fuel was banned, the army switched to standard (civilian issue) sodium-based LRP, but found that unacceptable valve wear was occurring at just 1,000 kilometres!
The situation became so bad that the army was given special permission to continue using leaded petrol until 1997. By then, many Heglunds had been pensioned off, and others have been fitted with special valve seats. But the remainder, now using a potassium-based additive at FOUR TIMES the recommended dose, are requiring valve clearances to be adjusted every 2,000 kms. Cylinder head life on these engines is currently a mere 10,000 kms (about 6,250 miles).
The problems faced by owners of some turbocharged cars have been equally horrendous. Early SAAB turbo engines didn't have hardened valve seats, and Swedish owners wer therefore forced to use lead substitute after 1992. Newer (pre-cat) turbo models (both SAAB and Volvo) often used it, as well, because of the poor availability of Super Unleaded. The terrible damage caused by sodium-based LRP nearly put Sweden's largest turbo specialist out of business: turbine blades became so badly corroded, and rebuilt turbo units were failing so rapidly, that the normal one-year warranty had to be withdrawn.
The most damning indictment thrown up by the RMIF seminar is the fact that this information has not previously been put into the public arena for open discussion. Scientific data has long been available - the aero-engine industry knows all about high-temperature corrosion and has totally condemned sodium additives. (Aviation spirit is always fully leaded, everywhere in the world.) Potassium compounds have also been linked to corrosion problems. Major petrol companies, like Shell and Esso, have carried out tests which confirm the unsuitability of these particular compounds - yet there's every likelihood that they'll be used in some brands of British lead replacement petrol.
The Swedish Army's Heglund troop carriers are, admittedly, an extreme case: towing a maximum weight trailer uphill is probably the nearest equivalent - and few car engines would be worked that hard continuously. But agricultural engines often are - and there are still plenty of British farms which employ an elderly petrol tractor for back-up duties. (Official US government data from 10 years back proved that agricultural engines wear out much more quickly on LRP than on leaded.)
If nothing else, the Heglund episode proves how well leaded petrol performs by comparison with LRG - the troop carriers didn't suffer valve problems on leaded. It also reinforces the validity of testing that was carried out for the Sainsbury supermarket chain, which was considering the introduction of sodium-based LRP in place of 4-star. Sainsbury decided against selling LRP when the bench-test engine, a Rover A-series, failed after just 30 hours at 4700 rpm. (Less than 2,300 miles at motorway speeds.) At the time, that test was criticised for being too harsh - but it was nowhere near as tough as the working conditions experienced by the Swedish army vehicles.
Our own government, meanwhile, tells us that we've got nothing to worry about. When 4-star goes, we'll all be able to use lovely LRP. And LRP, it assures us, will protect classic engines for all normal motoring. But in the very next breath it admits that the stinking stuff WON'T protect engines at motorway speeds! "LRP and AWAs... provide adequate protection in normal driving. If your car covers many miles... driving at motorway speeds or towing a heavy trailer or caravan, LRP or AWAs may not provide enough protection." (What? You want to drive your classic at seventy miles an hour? Goodness me! But that's not 'normal motoring'. Oh no! You're only expected to drive at forty in your funny old museum piece! And as for towing...")
The Department of Environment, Transport and the Regions (DETR) has put out an information document, "Making the Change, Moving to Lead Free Petrol", from which the above quote was taken. LRP means 'lead replacement petrol', and I assume that AWA means 'anti-wear additive' - the jargon isn't explained in the document despite its 'questions and answers for idiots' format.
Predictably perhaps, the entire basis of the document is flawed. It starts: "As part of a European strategy to reduce pollution from road traffic and improve the air we breathe, leaded petrol will be banned from general sale from 1st January 2000." In fact, the banning of leaded petrol will have quite the opposite effect. More Super Unleaded will be burnt, so more carcinogenic effluent will result. Meanwhile, those cars which have their ignition timing retarded, to run on lower octane Premium Unleaded, will be less efficient and will therefore produce more emission products per mile. (But the government recommends that you do this, so it must be better for the environment, mustn't it?)
Quite apart rom this kind of unfounded psuedo-science, the official document actually issues instructions which could result in engine damage:-
Question - "What do I do if my car requires the octane rating of leaded petrol?"
Answer - "If your car requires leaded petrol for its octane rating only, you should use Super Unleaded petrol where it is available or LRP."
Er... except that (as we've seen from the Swedish case studies), this can knack your valve seats if the LRP happens to be sodium-based. And if it's a turbo engine, you'll destroy the turbine blades too. Never mind, just send the bill to the DETR...
So what's the answer? The long-term (though expensive) answer is undoubtedly to fit the best quality hardened valve seats that are available for your engine. And hardened valves. Along with special new guides. Then use either Premium or Super Unleaded according to octane requirements. But, even on the simplest engine, that work will cost hundreds of pounds - if you get the job done on the cheap, by cowboys, be ready for the inserts to drop out. Oh, and by the way, you should still expect to suffer increased valve guide/stem wear. Not to mention pump failures on Lucas fuel-injected cars.
For many people, hardened seats aren't an option - either because they can't afford it or because their engine won't physically take them (and that aaplies to a number of relatively common motors). So they'll have to use some form of lead substitute. Test results have proved, quite conclusively, that phosphurus-based compounds are considerably better than either sodium or potassium - the best known phosphorus additive is 'Valve Master', by Du Pont. (Manganese has been suggested as a lead substitute, but there's insufficient data to recommend it yet.)
However, there's also ample evidence to show that none of these substitutes is anything like as good as lead itself - indeed, based on the Swedish experience, it has been suggested that about 100,000 British cars will suffer premature engine failure each year as a result of this ban. Justify that in environmental terms, please, Mr Prescott.)
Almost certainly, some petrol companies will blend the cheapest (sodium or potassium-based) compounds into their LRP. These are effectively useless - and could even be destructive. One point of concern, highlighted by the RMIF, is that you won't necessarily know which lead substitute compound is being used by which petrol company. Mixing of different compounds, from tankful to tankful, is definitely not recommended. But the common practice within the industry, of bulk selling between the various fuel companies, means that consumers are likely to mix compounds without realizing it.
That's why the Federation of British Historic Vehicle Clubs is pressing the government to ensure that suitable grades of 'pure' unleaded (including 98 octane) will be available on each site which previously sold 4-star, along with a selection of properly identified, bottled additives. Then classic car owners would be able to make their own, informed choice of compound - and stick to it. But the government's response, according to the DETR press office, is that this will be for the petrol companies to decide. So, as now, if you live in a rural area, you might have to travel fifty miles to find any unadulterated Super Unleaded to go with your bottle of Valve Master.
Incidentally, the official line is that, when adding the compound yourself, you shouldn't exceed the recommended dose that's printed on the bottle. But there is some evidence, from the US Environment Protection Agency, that doubling the dose may cut down wear under heavy load conditions.
Other than choosing the best compound from a bad bunch, the most important factor when driving on lead substitute fuel is to keep engine temperature down. This may mean lower speeds and/or less load. It certainly means a well maintained cooling system, and correct carburettor/ignition settings. (Though a slightly rich mixture may actually be best.) One trick that Scandinavian enthusiasts have learned is to set valve clearances slightly loose, by one or two thousandths of an inch. This lets the valves rest on their seats fractionally longer and should result in better heat transfer. It also gives more warning of the onset of valve seat recession (VSR). When VSR occurs, the tappet clearances close up, valves may be held away from the seat, and - if that happens - they'll burn. So learn to live with noisy valve gear: start worrying when things turn quiet.
The people who are probably going to suffer most as a result of this stupid, unscientific, politically motivated lead-ban are those with side-valve engined vehicles. The exhaust valves on a side-valve motor tend to run hot anyway and - living, as they do, in the block - seats are more difficult to replace. Unfortunately, on some designs, there simply isn't enough material to allow insert machining to take place. Added to which, Ford side-valve engines often had no separate valve guides - a passage was simply carved into the cast-iron. Sloppy valves therefore constitute a serious problem, and the absence of lead is likely to accelerate wear in this area.
I deliberately haven't touched upon the subject of so-called 'fuel catalysts'. Regular readers will know that I am about to fit a FuelCat to one of my vehicles. I will conscientiously report the results of running that engine on 'straight' unleaded - and some users do claim to have covered large mileages without problems. But I must stress that there is, as yet, no scientifically acceptable evidence to confirm that these tin-alloy pellets provide the protection required for soft valve seats.
One final thought. The research literature pertaining to LRP shows that these lead substitutes fail at high engine speeds, and/or high engine loads, because the coating that they leave on the valve seats tends to disintegrate at a lower temperature than 'real' lead. Which is why it's so important to keep combustion chamber temperatures down. Now, a proven method of lowering combustion chamber temperature is to apply water-injection.
This technique has been known for decades, and its value has been proved extensively on supercharged/turbocharged engines. It's not just another 'looney tunes' idea: major manufacturers have used water-injection - in both the aero-engine and automotive industries - as have top drag racers. The process simply involves introducing a pre-determined dribble of (usually) 50/50 water/alcohol mix into the inlet manifold. The apparatus needn't be complex and shouldn't be too expensive. So here's a challenge: will somebody come up with a neatly engineered WI set-up, and test it on an engine using lead replacement fuel? I'll bet that valve seat recession would be noticeably reduced and I wouldn't be at all surprised if the product became a huge commercial success!
David Landers
What is YOUR opinion on this controversial subject? E-mail your views to us at . Or you can contact The UK Department of the Environment Transport and the Regions direct - from their website you can email your views to them. For other unleaded fuel information in the archives, click here and here. For the official Government news, take a look at this page. Check out http://www.secant.co.uk/unleaded/ for loads of interesting stuff, including a marque guide. The BBC's 'Watchdog' programme covered the issue in October 1999; click here. Bayford Thrust has started selling leaded 4-star again (February 2000), click here for forecourt locations. And many thanks to Mike Millen for providing us with this very interesting link on the subject; take a look at 'The Lies of Unleaded Petrol Pts. 1-3' on this page: http://www.peg.apc.org/~nexus/.
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