Perhaps you see WD-40 as a fix-all. Handyman Gator, for instance, once graced the Daily Dot with an unconventional use for the spray-on lubricant that he swore by.
However, as one mechanic will tell you, there’s one car part you should never, ever use WD-40 on.
The advice comes from creator Scotty Kilmer (@scottymechanic.us). His Sept. 3 video has gotten more than 186,000 views as of this writing. In it, he implores people not to spray WD-40 on a fan belt, even if it’s making noise.
“Fan belts are made to run dry,” he notes. “If you put lubrication on them, it can slip.” He then takes people through a bit of automotive history, saying that on older cars like a ’94 Toyota Celica, a squeaking noise typically meant that the fan belts had to be manually adjusted.
Today, however, he notes fan belts typically “use only one gigantic serpentine belt with automatic tensioners that you never have to adjust.”
If your fan belt is making noise, it’s either that it has stretched out and needs to be replaced, or it’s symptomatic of some other problem like a bad water pump or alternator, Kilmer explains.
“Spraying oil on it isn’t going to fix that,” he remarks. “And I mean, don’t spray anything on it, even things that say ‘belt ease’ [or] ‘belt dressing.’ These belts are made to run dry. Do not lubricate them.”
What is belt dressing?
If you’ve never heard of belt dressing before, rest assured that it exists, and a quick search on Amazon will reveal many options for something Kilmer says you should never spray on your fan belt.
According to Blain’s Farm and Fleet, “Belt dressing, also known as belt conditioner, is a specially formulated spray designed for use on rubber belts found in various machinery, including cars, trucks, lawn mowers, and tractors. Its primary purpose is to soften the rubber, which keeps it from drying out and slipping.”
The site goes on to explain, “Belt dressing works by penetrating the rubber material of the belt to keep it flexible and grippy. This not only keeps the belt in place but also maintains the proper tension necessary for effective operation. By softening the rubber, belt dressing causes friction and prevents the belt from hardening over time, which is a common cause of wear and tear.”
The site also recommends applying it every 3,000 miles.
But one redditor tried it and was so traumatized that he was moved to post to the r/f150 forum last year.
“Turns out this sh*t is practically blinker fluid/snake oil and hasn’t been relavent in the automotive world for like 50yrs,” he reported. “The squeak not only became 10x louder, but it never went away. I drove for about 1.5hrs and I had to turn up the radio because it wouldn’t go away! The old squeak would go away once I hit the highway.”
@scottymechanic.us Stop Using WD-40 on Your Car Right Now #scottykilmer #cars #exhaust #mechanic ♬ original sound – Scotty Kilmer
What commenters said about WD-40
Commenters brought their opinions.
“It’ll make the squeak even louder if you do that,” one said, echoing the redditor.
“WD-40 is not a lubricant!” insisted one, even though the WD-40 official site dispels this myth on the WD-40 Myths page, saying, “While the ‘W-D’ in WD-40 stands for Water Displacement, WD-40 Multi-Use Product is a unique, special blend of lubricants. The product’s formulation also contains anti-corrosion agents and ingredients for penetration, water displacement and soil removal.”
“Don’t listen to him,” another counterpointed. “Belt dressing works well.”
Someone else took it even further, insisting, “WD-40 [is the] best solution for everything.”
The Daily Dot has reached out to Kilmer via TikTok direct message and to WD-40’s makers via email.
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