July 23, 2019

Ethanol: a classic threat?

Ethanol, the biofuel additive for unleaded fuels, is in favour with governments due to its ability to reduce the emissions of petrol-powered vehicles. A chemical compound created using natural substances such as sugar cane, ethanol can also be used to boost the octane rating of fuels. It sounds like a mystical elixir to solve all our problems, so why do classic car owners view it through furrowed brows?

Ethanol is hygroscopic, which means it absorbs water. It is also corrosive. This presents negligible problems for cars in frequent use where fuel is regularly cycled, but it’s bad news for classics that often spend the harsh winter months laid up hiding from the elements. Instead, ironically, it could be chemical elements causing problems from the inside out. Ethanol-treated petrol goes ‘off’ quicker and its propensity to absorb water and promote corrosion can lead to accelerated degradation of fuel tanks, pumps, lines and carburettors.

As part of the government’s Renewable Transport Fuels Obligation (RFTO), legislation originally called for ethanol to be added to unleaded fuels at a ratio of 5%. Talk has continued regarding officially upping this figure to 10%, but nothing has yet been confirmed.

In terms of protecting your classic from the possible effects of ethanol, it’s worth considering that there is currently no requirement for ethanol to be used in super unleaded, 97+ Ron fuels. However, some companies do still add the substance, and this can vary from region to region.

From a mechanical perspective, while there’s little you can do about fuel going ‘off’, updating fuel hoses will help as rubber lines certainly won’t last as long as they have in the past (you’ll now find hoses that are marked specifically as being ethanol-resistant, and nylon tubing will also last well). A water separator fuel filter can help ensure your air/fuel mixture is uncontaminated and we’ve also heard of people using a carburettor fogger to cleanse the chamber of potentially corrosive fluid before shutoff. Myriad fuel additives are available to help protect against lasting damage and, finally, it’s worth considering that ethanol will essentially melt fibreglass, so tanks or filler necks made from the substance will get increasingly leaky.

Removal of lead from UK fuels was also supposed to signal the end for older vehicles, but we found a way to carry on through additives and cylinder head modification.

So, are you concerned about ethanol and the potential problems it could cause your classic? Let us know what you think in the comments.   

I would like to know what petrol additives could be used instead of ethanol that will keep a carburettor clean, not damage rubber, pipes and tanks etc. And good for the environment.

Budgie, 27/07/2019