The Simple Trick to Tell When a Car Needs Waxing

You probably know that you need to wax your car regularly to keep it protected from the elements. And most wax manufacturers will claim how long their wax lasts for. But how do you actually know when your car needs waxing? 

In this article, I’ll explain exactly how you can tell that your car is ready for a fresh coat of wax or sealant. So let’s get started.

The Quick Answer 

You can tell whether a car needs to be waxed again by looking at the water repellency. If when you spray water on the surface, it forms beads which roll of the paint, then the car doesn’t need waxing. If the water stays on the paint and doesn’t form beads, then it’s time to wax the car.

Look at the Water Beading Properties

Since wax leaves an invisible layer to protect your car, it can be really difficult to tell when this has worn away and needs topping up.

I find that the easiest way to see much wax is still left on the surface, is to see how much of its water repellency is retained.

All waxes repel water, granted, some better than others. So it can be a good idea to take a photo or quick video of the water repellency that your car’s paint has a day or so after waxing.
This will give you something to compare it to in the future. 

Water repellency is one of the most beneficial things about using wax on your car. It stops muddy water sticking to the paint and making it more difficult to remove when washing without causing scratches.

Water Beading 

The best way to actually assess the water repellency is by misting your car with water.
Don’t blast it with the hose, or it’ll push all the water off the surface. 

So instead lightly mist the car with water. The aim is to create a beading effect.

Two things can happen to an old wax.

  1. The beading ability becomes none existent and the water will evenly coat the paint
  2. The beads will be less pronounced and look flatter

Of course, the first point, usually happens to very old wax. If the surface has no water repellency properties then you should apply a wax asap because there is little to no protection on the surface.

Only do this after washing your car. If there is any dirt on the surface, it’ll mask the wax and you won’t be able to tell if it needs topping up.

If the water beads are flatter, then it’s usually a sign that the wax needs topping up with a spray wax or with a proper coating. 

This car doesn’t need waxing because the beading is very pronounced.

There is some level of beading so this car still has some protection on the surface but could do with waxing fairly soon.

This car has no wax left on the surface because the water does not bead at all.

Water Sheeting 

Some waxes don’t actually cause much beading, but instead they sheet the wax off the surface. 

The best way to assess whether the wax is still in the surface with this method, is to just use a very light pressure hose and rinse the car. 

The quicker the water is pushed off the surface, the stronger the wax is. If the water lingers on the paint, then it’s time to apply a fresh coat of wax.

The water sheets off this car quickly so it doesn’t need waxing
The water doesn’t sheet off, and lingers on the paint so it needs waxing

How Often Should You Wax Your Car?

You should apply a fresh coat of wax to your car whenever you start to see the hydrophobic (water repellency) properties diminish.

Try the steps above to see if this has happened. If it has, then apply a fresh coat next time you wash it. Or if you don’t have time, then apply a spray wax after washing to top up the protection.

Take a look at this article I’ve written about how to prepare your car for waxing to get the best results and durability from your wax.

It can be good to stay ahead though, and wax your car before you see the water repellency become less significant. This way, you ensure that your car has protection from UV rays which can cause fading over time.

How Long Does Car Wax Last?

This has to be one of the most commonly asked questions in the car care world. Probably, because pretty much everyone gives a different answer.

It really depends on a few different factors.

  • The type of wax you’re using
  • How well the surface was prepared before applying
  • How exposed your car is to the elements

Take this example.

A car that has been coated in a layer of natural Carnauba based wax, on top of paint that has been washed and dried, but not decontaminated, and is driven daily and stored outside.

In this case, you’ll be lucky to get a months worth of durability out of the wax.

Take another example. A car that’s coated in a sealant-type wax designed for durability, the surface was decontaminated, clayed, and old wax layers were removed before applying. The car is stored in a garage and only driven a few times a week in nice weather.

Well, in this instance, you could get up to 12 months durability out of the wax.

Generally, waxes last around 2-3 months before you need to reapply them. It’s super important to keep this protection topped up to make sure the finish is protected at all times.

Check out my guide to how long waxes last, for plenty of examples.

How to Make Car Wax Last Longer

There are actually a few things you can do to make the car wax last a little longer. Here are some of my top tips.

  • Use a durable synthetic-type paste wax, instead of a natural high-content Carnauba wax.
  • Store the car inside or undercover. This stops the hot sun or rain from degrading the wax.
  • Apply the wax to bare paint. Prep the surface by decontaminating and removing old layers of wax. Take a look at this article I’ve written about how to prepare your car for waxing.
  • Use a mild pH neutral car shampoo to wash your car. Never use dish soap, and don’t use a traffic film remover.
  • Keep the paint clean to avoid contaminants like bugs, tree sap and bird mess from eating into the wax and reducing its life span.

Looking for a durable wax option? Check out my guide to ceramic waxes which are well known for their excellent longevity.

Thanks for reading! I hope you’ve found this article helpful. Don’t forget to check out the rest of the blog to learn more about car care and detailing.



Heather is a professional car detailer & valeter based in Cheshire and the owner of Auto Care HQ. A familiar face in the car detailing community, she has written over 200 car detailing guides on and has produced over 165 videos on the Auto Care HQ YouTube channel.

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