Hammerite Underbody Seal with added Waxoyl

Tested for: 4 years
Has the vehicle been used in rain, mud, salt and snow? Yes
Has the Waxoyl peeled off? No
Recommended? Yes

Price: £23.11 per 2.5 litre tin (pictured) at date of publication. Click here for up-to-date price on Amazon..

You’ll read plenty of negative reviews of about Waxoyl, and other tar-like, solvent-based products like it, but not from me. The key factor is that it needs bone dry metal to adhere to, otherwise it’s more trouble than it’s worth. Most people aren’t prepared to put in the necessary time preparing the metal.

I have a hunch that the more expensive underseal products are bought by people who think more carefully about what they’re doing. But if you’re anal about it, Waxoyl works.

I applied Hammerite Underbody Seal to the entire chassis of a Series Land Rover in 2014, using a paintbrush, and it’s showing no signs of peeling in 2018. With the chassis completely dry, every inch was thoroughly attacked with a wire brush to ensure the metal was as clean as possible. Dirty corners were dug out with a screwdriver, scrubbed with a wet toothbrush, then left to dry for a week or blown with a hair drier. It sounds ridiculous but it’s the only way for this to work (unless you have a shotblaster).

Waxoyl instructions
Waxoyl 2.5-litre tin. Coverage: 5sq. meters.

How not to apply Waxoyl

A few years ago I took a Land Rover Discovery 1 for a professional treatment of Waxoyl (not quite the Hammerite Underbody Seal stuff you get out of a tin) at a well-known specialist, and watched the entire process. The vehicle was steam-cleaned, then left to drip dry overnight. It was winter in England, cold and damp, and one night wasn’t long enough to dry it. Nevertheless, the application went ahead, which seems to be standard procedure. I’m not aware of an underseal specialist that leaves a vehicle to dry for more than one night.

The boss then told his employee to clean the car for me. That was a decent gesture, but presumably he meant for it to be done after the Waxoyl had been applied, not before. So the car was jetwashed then immediately Waxoyled, while the wheelarches and sills were damp from overspray.

Within 9 months the Waxoyl was falling off. After 18 months the car needed a complete new sill, and welding to both rear wheel arches. Total cost: over £1000.

Preparation is everything. But Waxoyl products aren’t so bad. I’d buy Hammerite Underbody Seal again.

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