Fuel Information

Introduction

Using unleaded petrol in vehicles designed for leaded

Leaded petrol availability

TVO

Bio-fuels

Additives

Introduction

The nature of road fuel has changed significantly over the past quarter century, with inevitable consequences for those wishing to use vehicles designed in earlier times. The changes have been driven by a combination of environmental concerns about air quality and advancing engine technology.

Perhaps the most significant change has been the demise of leaded fuel. Tetra ethyl lead was first used as an anti-knock fuel additive in America in the early 1920s. It was initially introduced as an ‘anti knock’ agent, or octane enhancer, but it was soon realised that it also provided a significant degree of protection to valves and their seats. Other additives, additional refining or a combination of both can provide an acceptable octane rating without the use of TEL, but no other additive is as effective in protecting valve seats from wear.

In Europe, TEL displaced the various alcohol compounds that had been used for the same purpose and by the mid-1930s was the additive of choice. As compression ratios increased in the post-1945 era, TEL became an essential component in all grades of petrol, with the highest so-called 5-star grade using up to 0.8g TEL per litre in the 1970s.

By the mid-1970s, pollution from road transport was becoming a serious problem especially in built-up areas and along major trunk routes. The small lead content was only a part of the problem: unburnt hydrocarbons and soot emitted as a result of incomplete combustion contributed significantly to poor air quality. Efforts were made to tackle this in two ways: reducing the harmful content of fuel and improving engine efficiency to ensure that fuel was burnt completely.

One of the first steps to reduce the harmful content of fuel was to phase out 5-star petrol (which became unobtainable by the early 1980s) and to reduce the TEL content of other grades. By the end of the 1990s, the TEL content of 4-star grade petrol was 0.15g per litre.

The efforts to improve engine efficiency went in two directions – so called ‘lean burn technology’ favoured by Ford, and the use of catalytic converters to ensure complete combustion. The decision to follow the latter course meant an end to the use of TEL since it is not compatible with the catalyst.

More recent changes to fuel specifications include requirements for road fuels to include a “renewable” element.

Changing fuel specifications invariably cause problems for owners of older vehicles, and it is not always obvious what the cause – or the remedy – might be.

FBHVC has been active in monitoring the effects of changing fuel specifications and commenting accordingly. It undertook significant testing of fuel additives in the run up to the general ban on leaded petrol at the beginning of 2000, and also lobbies for concessions where appropriate.

Two booklets were published and further articles on fuel quality have appeared in the FBHVC Newsletter. This page provides a summary with information about where further material may be found.

Using modern unleaded petrol in vehicles designed for leaded

In the late 1980s, it was obvious that there would come a time when leaded petrol would cease to be available. In 1991, a sub-committee of the Vintage Sports-Car Club published a booklet entitled “Valve Seat Recession – Use of Unleaded Gasoline in Older Engines” which was made available through FBHVC.

This booklet outlined research undertaken into the problems of valve seat recession, and suggested how such problems may be alleviated either by modification (such as fitting hardened valve seats) or the use of fuel additives or a combination of both.

Other problems occurring at this period included problems with vapour lock, leading some to add kerosene to petrol in order to make their engines run smoothly – although not recommending the practice, FBHVC obtained a general licence from HM Customs and Excise (as it then was) to allow kerosene to be used for this purpose in pre-1940 vehicles.

In 1993, FBHVC published another booklet “Fuel Problems – Use of Modern Petrol in Older Engines”. This was prepared by the same team who had produced the earlier book who had by then become a sub-committee of FBHVC. The second booklet covered topics such as overheating, poor starting and loss of power by reference to scientific literature on the subject and again offered suggestions to remedy the problems.

Hard copies of both these booklets are still available on application to the Secretary.

Leaded petrol availability

Following intense lobbying by FBHVC and FIVA, the European Directive (reference 98/70/EC) imposing the general ban on the sale of leaded petrol included a derogation allowing the continued sale of small quantity of leaded petrol in controlled circumstances for use in vehicles that could not practically be adapted to run on unleaded.

That Directive was transposed into UK law by means of Statutory Instrument 1999/3109, the Motor Fuel (Composition and Content) Regulations 1999, which included clauses allowing the sale of leaded petrol to members of the historic vehicle community by means of a network of fuel outlets that had to be registered with FBHVC for the purpose.

In the initial years, nearly 200 fuel retailers were registered, but the demand for leaded petrol has dwindled as owners have found alternative ways to avoid fuel-induced engine damage.

Only the following fuel stations (listed in alphabetical order by Post Code) were registered with FBHVC as retailers of leaded petrol to BS4040 at the end of 2009.  At the time of writing, April 2010, there is concern that the point may have been reached where the distribution of leaded petrol may no longer be economically viable.  Unfortunately, FBHVC is not always informed when a garage ceases to sell leaded petrol, so it is wise to check availability before travelling.

TVO

In 2006, FBHVC looked into the use of ‘red diesel’ and TVO in tractors. TVO has not been marketed as such since the 1970s, so owners of TVO tractors either had to convert to run entirely on petrol (not always possible) or create their own TVO from kerosene heating oil.

Not only was this illegal for use on the road (because kerosene, like ‘red diesel’, is a ‘rebated’ fuel on which normal duty is not charged) but because of the way the law is worded, it was also technically illegal to use home-brew TVO in a tractor on private land if that tractor is licensed for use on the road.

FBHVC took this matter up with HM Revenue and Customs, and the result was a special licence allowing members of FBHVC subscriber organisations to mix rebated kerosene with other non-rebated fuels in the tanks of their tractors – mixing with red diesel is not allowed.

Members of FBHVC subscriber clubs may obtain a copy of the licence on application to the secretary.

Bio-fuels

See NEW page on Main menu panel to the left

Additives

In the run up to the withdrawal of leaded petrol at the beginning of 2000, FBHVC tested various additives that were claimed to provide a measure of protection against valve seat recession. The products that were found to provide similar protection to fuel containing 0.15g TEL per litre are listed below – several have since been withdrawn from the market as the number of vehicles requiring additives has fallen over the last decade.

The final additive, Tetraboost, was not tested, but FBHVC carried out an analysis of its composition and has confirmed that if the dosage instructions are followed correctly, Tetraboost adds 0.15gTEL per litre (the equivalent lead content of 4-star petrol) to unleaded petrol.