Unleaded Petrol.

The Problem:

As you are probably aware, leaded (4 star or "super") petrol will have been withdrawn throughout Europe by the beginning of this year (2000). Although this does not present a problem for the majority of vehicles, especially modern cars, designed to run only on unleaded, it may prove a problem to owners of older or classic cars. Many of these can be adjusted to run smoothly on unleaded, but a significant number will not be able to run on unleaded petrol without serious damage. This alternative "millenium bug" will affect the owners of many old and classic vehicles.

Unleaded and the 2cv:

The good news for the majority of "A series Citroen" (2cv, dyane) owners is that their cars should be able to use unleaded with no alterations, additives or major adjustments to the engine.

All 602cc 2cvs should be able to use unleaded petrol without any engine damage. Citroen tested engines using 98 octane unleaded in 1983 and 1987. However, the following precautions should be taken:

Ignition system should be in good condition and correctly set (no retarding/advancing should be necessary). The car should not pink uphill or backfire downhill if properly adjusted. If it does, don't use unleaded, or use "high octane" unleaded.

Exhaust system should be of the correct type, correctly fitted and in good condition (to ensure the right back-pressure and temperature at valves).

The valve clearences should be set to 0.25 mm (0.010 "). Note that this is wider than the measurements given in the workshop manual.

The fuel system, air filter and carburettor should all work properly. Some of the substances in unleaded fuel can cause the fuel line to perish, causing bits to find their way into the carburettor, or worse, leaking pipes. Replace if in doubt. A simple fuel filter is a useful addition.

The cooling system should be effective (check the fan, oil cooler (should be clean), and cowling).

Ami, Dyane, Mehari and van variants (with a higher (9.0:1) compression ratio) should be O.K. on 98 or 97 octane unleaded but will need their timing retarded slightly. 95 octane unleaded should not be used.

However, I believe older cars (with 375, 425 or 435 cc engines) may not be as well suited to unleaded petrol. It may be advisable to use additives with these engines (see below).

Petrol Additives and Devices:

If your car is not compatible with unleaded petrol, or you'd prefer not to use only unleaded petrol yet, a number of additives and devices are available, which claim to replace the lead in unleaded petrol. These may, or may not work, and only anecdotal evidence exists for the majority of these.

Recently, though, a number of fuel additives were tested by MIRA (the Motor Industry Research Association) on behalf of the Federation of British Historical Vehicle Clubs. The additives and inline 'fuel catalyst' devices were exhaustively tested using B.M.C. A series engines (nothing to do with Citroen's "A series"). Of the 12 additives and devices tested, only 4 were found to reduce valve seat recession, and pass the test. These additives, which do work were:

SuperBlend Zero Lead 2000/Superblend 12 lead additive

Miller's V.S.P. Plus (This is also an octane booster, and so should prevent pinking or improve performance).

RedLine Lead Substitute

Valvemaster

The other additives, and in line fuel devices which were tested did not pass. Other additives and devices which were not tested may work, but until genuine, independant evidence demonstrates this, it is unknown.

Lead replacement Petrol:

"Four Star" or "Super" petrol continues to be available, but this is now called "Lead Replacement Petrol". This may be used as a direct alternative to old "Four Star" petrol, as it contains alternative substances instead of lead. I am unaware of how effective this will prove to be.

I have compiled this information from my own experience, as well as a number of reliable sources. However, as always, this is intended as "friendly advice", and I cannot accept responsibility for any inaccuracies/errors contained within.

Will Rolt

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