If you’ve followed The Motorcycle Obsession for long you’ll probably at some point have seen me singing the praises of GT-85, a PTFE-based multi-purpose lubricant. It’s a bit like WD-40 but different.
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The spray is excellent at displacing water and over the years I’ve argued that it’s a good idea to coat your bike in the stuff, relying on it to protect metal bits against the slings and arrows of winter. But it turns out I’ve been wrong all this time; GT-85 is not really effective as a bike protectant.
This stunning revelation comes thanks to my friend John Milbank, who writes for Bike Social. A while back, he spent several months researching 10 different products that riders use to defend their bikes against British winters. These products included those that actually claim to be protectants and those, like GT-85, that are widely believed by riders to serve said purpose. The 10 products were: ACF-50, XCP Rust Blocker, Scottoiler FS 365, SDoc100 Corrosion Protectant, TechCote ACS TC200, Muc-Off Motorcycle Protectant, WD-40, GT-85, Valvoline Multi Spray and Motorex Moto Protect.
To test their effectiveness John got hold of several metal plates, to which he applied the various protectants. Then he spent the next seven months torturing the plates.
“Every day, morning and evening, each plate with a 5-percent solution of road salt,” he explained.
Then, once a week, he’d rinse the plates by spraying them with a hose. He didn’t reapply protectant to any of the plates save the one with Scottoiler FS 365 because, in fairness, the instructions say that it is water-soluble and needs to be reapplied after every ride. He kept this up for week after week after week, altered his methods slightly to up the torture level and carried on for many weeks after that.
The plate coated with GT-85 didn’t even make it through the first week before signs of corrosion started appear. Interestingly, the product most people see as its main competition, WD-40, lasted longer – holding on into the second week.
“A lot of people rate GT-85 over WD-40 and assume that it’s better at everything” John said. “Clearly it’s not. But remember: neither of these products are sold as a corrosion protectant.”
How to Ride in the Rain
There’s a lot of fascinating information to be had in John’s research. My personal take from his work is that I’ve invested in a can of ACF-50. It didn’t perform as brilliantly as some others in John’s test but the combination of (relatively) reasonable price and easy application make it the choice for me. Especially in light of the fact I clean my bike quite regularly and will be reapplying the protectant after each wash.
That fastidious behavior is probably the reason I had come to praise GT-85 so highly. It was doing its job in displacing water, and my meticulous cleaning schedule (with re-application) was keeping corrosion at bay. I’ll still be applying GT-85 after a wash, to help push out moisture from nooks and crannies, but I won’t be expecting it to protect the bike through the week.
When John was telling me all about his research, he poked fun at himself for being such a nerd but I have nothing but praise for his hard work here. This research took a lot of time and effort and dedication, with almost all of it being done on his own time. I have pleaded with him to consider doing a similar test for chain lube*.
* An update on the SDoc100 White Chain Spray 2.0 review, by the way: the company’s head of research has gotten in touch with me and is eager to determine what, if anything, went wrong with the spray I used. I’ll keep you updated on his findings when I know them.