When should you apply a fuel tank sealer in your car or motorbike?

Deciding whether to seal the inside of a fuel tank is a common issue faced during vehicle restoration and maintenance projects. Let’s look at some of the factors influencing the decision you might take for your project.

Classic vehicles rolled off the production line at a time when they were expected to deal with leaded, ethanol-free fuel. Times have changed and so has fuel. Today’s petrol is unfortunately harmful to many older fuel tanks, so applying a fuel tank sealer is a common feature of restoration projects.

Years of use can seriously degrade the inside of a fuel tank. Once corrosion begins, it can lead to a weakening of the tank and, eventually, pin holes or more serious failures. A leaky tank is not a good sight on an otherwise sorted vehicle.

The effects of lead and ethanol

In the days of leaded fuel, the lead acted as a barrier that prevented or slowed down the corrosion. Classic cars that have been running on unleaded for years are therefore often the victim of corrosion inside the tank.

The ethanol (alcohol) additive in modern unleaded fuel has created another problem. It can degrade the polyester-based linings that were often a feature of older vehicles’ fuel tanks.

A solution to these problems is Rustbuster’s Slosh Fuel Tank Sealer suitable for lining steel, aluminium and GRP (glass fibre) petrol and diesel tanks. Tests with dilutions of up to 85% corn ethanol showed no degradation or softening of the sealer. This confirms its ability to protect against the ethanol content of modern fuel.

When did fuel tanks start to be made for ethanol fuel?

It is hard to pinpoint a date from which fuel tanks were designed to accommodate ethanol-based fuel. Unleaded petrol went on sale in the UK in 1986 but wasn’t widely available for some time after that. European rules demanding unleaded-only vehicles became effective in October 1993 and leaded petrol was banned in 2000.

This long period of  crossover between the two fuel types means there isn’t a hard-and-fast rule for when fuel tanks were made with ethanol-based fuel in mind. Owners of cars manufactured between about 1986 and the early nineties may therefore do some research into their particular vehicle, or elect to play it safe and look at protecting their tank. Even tanks from cars dating from the early nineties onwards may be showing signs of age and owners may decide to apply a sealant.

Does a brand new tank need to be sealed?

Opinion is divided on whether there is a benefit in lining a brand new tank. One view is that a new and high quality tank is unlikely to corrode any time soon, especially if it is used regularly and often topped up with fuel.

On the other hand, some people worry that a vehicle not used regularly and stored with a near-empty tank could suffer from corrosion if a sealant is not in place.

Advocates of sealing a new tank also point to issues like porous welds leaking over time, or fine cracks opening up due to stresses around mounting points. There is also the argument that sealing is a ‘belt and braces’ approach to protecting your investment in a new tank.

At Rustbuster we see this is a case for customers to balance the pros and cons, making an informed decision based on all the factors.

Fuel tank lining is achievable for DIY restorations

The beauty of using a fuel tank sealer is its simplicity. Once you have cleaned and prepared the tank interior there’s no brushing or spraying: just a simple pour-and-shake process. The job should take less than an hour, but it will deliver years of trouble-free performance.

The fuel tank sealer does much of the work for you, working its way into seams and sealing pin holes. If the tank is suffering from more significant holes or cracks, either welding or sealing them externally with an epoxy repair filler may be required before applying the sealer.

Rustbuster’s fuel tank sealer products

Here at Rustbuster we have a range of fuel tank products that have been used thousands of times by classic car and bike owners. Please check out Slosh Fuel Tank Sealer and let us know if you need any more information or help to give your tank the protection it needs.

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