PENETRATING FLUID

Say goodbye to rusty fasteners with the best penetrating spray

- Tom Barnard

SEIZED nuts and bolts are the most frustrating part of any motoring DIY, with the potential to turn a quick job into a mammoth task. Whether caused by overtightening or corrosion, a fastener that refuses to budge will soon become rounded as tools slip off, making it even more difficult to remove.

In the worst case the fastener will snap, leaving you with no choice but to reach for the drill or welding torch.

Soaking any stubborn-looking nuts and screws in penetrating fluid will give you by far the best chance of getting them off cleanly, saving you time and meaning you should be able to reuse the fastenings instead of searching for a replacement.

While many all-purpose lubricating sprays will claim to have a penetrating release action, a specialist spray promises to be more effective. We racked up the rusty nuts to test seven at a variety of price points.

How we tested

WE assembled six identical nut and bolt combinations that had been covered in salty water and left to rot outside for more than a year. We sprayed the test fluids into the top of the nut and watched how far the liquid tracked down through the thread after 10 minutes. We then measured the torque needed to undo the nuts.

As not all fastenings are easy to reach, we also used rusty nails placed upright in a pool of the fluid to test its ability to track upwards through corrosion.

Finally, we gave points for cans that were easy to use and good value.

Rocket TT

Price: £5.49 Size: 450ml Cost per 50ml: 61p Contact: mymotorworld.​com

WE had to double check the samples to make sure we'd got the right product because we didn't expect the all-purpose Rocket TT to perform this well in our tests.