A SIMPLE DIY repair using a £3 garage essential could be ruining your car, according to a mechanic.
Scotty Kilmer, who benefits from over 50 years of experience in the motor business, urged drivers to avoid the seemingly harmless hack to solve an irritating problem.
A squeaky drive belt can make even short trips feel unbearable, filling the car with a high-pitched squeal as you sputter along.
It may seem like common sense to pop a bit of WD40 on it to loosen it up and beat the squeak.
However, Scotty made clear that this is never an option.
Speaking on his YouTube channel, he explained: "WD40 is a lubricant but you don't want to spray it on rubber drive belts.
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"If the lubricant gets in there...it slips and it doesn't work right.
"These belts are meant to run dry.
"You don't lubricate them with anything, especially not WD40."
If your drive belt starts to slip it could play havoc with your car's ride.
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Not only can it actually make the squealing sound worse, but it can also knock out your air conditioning and other features like power steering.
And if it's allowed to continue too long, the extra strain could cause your engine to overheat, leaving you stranded on the roadside until it cools.
Instead, Scotty revealed that a noise from your dry drive belt is a good sign to replace it rather than trying to use a lubricant.
A spare only costs around £10 and can be installed yourself if you know how or done cheaply at a local garage.
Plus, if your car doesn't have an automatic drive belt tensioner it could just mean the belt is a little loose - which is even easier to resolve.
All you have to do is get the bolts around the belt's casing tightened or loosened as required.
He also explained that, if you do get some oil or WD40 on the belt by accident, the best thing to do is to spray that off with carburettor cleaner before it begins to slip.
It comes after motor specialists shared their picks for the five best cars you can buy for under £5,000.