The best underseal to protect your car from rust

Keep rust at bay with these easy-to-apply products and save yourself nasty repair bills.

The underside of a 4X4

by Ryan Gilmore |

Most people will turn to better fuel economy or better safety as the biggest leap in car design in the last 20 years, and it's easy to see why. Even larger cars are now capable of 50mpg and the smallest of city cars are capable of a five-star NCAP rating. But there's something else that's come on in leaps and bounds, rust protection.

RELATED: Rust converters and rust repair: Parkers' 'how to' guide

Take a peek underneath any car a few decades ago and you'll either see the worrying signs of rust forming or a thick black coating of primitive underseal, often made of bitumen. Older cars have their fans for various reasons, but rust protection was never one of them and steps need to be taken to avoid expensive damage. If you do happen to own an older car, or you just want a little more protection, aftermarket underseal (or underbody protection) is an effective way to keep your car safe from the elements.

How does underseal work?

The underside of your car is subjected to a lot of wear and tear while you're driving around. From stones flying underneath it to salt, water and other contaminants it can quickly become a breeding ground for rust. And as the underbody of your car is crucial to your car's structural rigidity, failing to stop rust can cost you a fortune in the long run.

Underseal works as a thick layer of protection that'll ensure that rocks and stones bounce off and that salt and other debris doesn't have the chance to begin rusting your car.

The best underbody protection

Bilt Hamber Dynax UC

Great Pick
Bilt Hamber Dynax UC
Amazon

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Our top choice for underbody protection, Bilt Hamber Dynax UC, is a clever, see-through wax that offers top-notch protection without changing how your car looks. The wax is durable and 'self-healing' to ensure that you get full coverage and the fact it's an aerosol means it's really easy to apply, even to awkward areas. And if you're worried about rust (i.e. you own an old British sports car), Bilt Hamber also sells a version for protecting internal cavities that pose a rust threat.

Hammerite Underbody Seal

Best Value
Hammerite Underbody Seal
Amazon

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The old faithful of rust protection, Hammerite Underseal, is as basic as it comes. It comes in a one-litre tin and can be applied with a paintbrush making it an old-fashioned option for rust prevention. The coating protects the undersides from salt and rocks, and the inclusion of Waxoyl will help keep rust at bay while also sealing in existing corrosion, so it doesn't spread.

Liqui Moli Bitumen Underbody Protection

Popular Choice
Liqui Moli Bitumen Underbody Protection
Amazon

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A classic choice of underseal with a modern twist, Liqui Moli Bitumen Underbody Protection makes use of bitumen to seal and protect the underbody of your car but is sprayed on for easier application. Unlike the Hammerite, you'll need to remove existing rust before coating your car, but the quality is excellent.

Jenolite Rust Shield

Top Pick
Jenolite Rust Shield
Amazon

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A clear coating for rust removal, JENOLITE Rust Shield is a tough layer that can be applied to all metal surfaces to give excellent protection against rust. It can be used on clean or previously rusted metals and is a solid choice if you don't want the underside of your car coated in black.

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