The day I bought the Grant’s-brand Auto Detailing Dirt Guard at Harbor Freight, I was casually walking around the store after having dropped my car off to get an oil change. After buying it, I made a stop on my walk back to the shop to get lunch and got asked by three people along what exactly the neon orange plastic thing was for. I told them it was for car washing. When they asked if it worked, I responded, “Well, we’re going to find out.”

I had my doubts that a piece of ornate plastic was going to make a meaningful difference in keeping car washing water clean. But this little contraption proved me wrong – it does the job far better than I imagined it could.

The visual oddity of the item was what caught my eye at my local Harbor Freight Tools store in Mayfield Heights, Ohio. After almost walking by it — and then spending a few seconds of trying to figure out what it was for while noticing its $5.99 price tag – I decided it was such a wacky product that it deserved to be tested.  Though I had initial enthusiasm for trying out the dirt guard, it was months before I first used it when I gave my 2008 Yamaha FJR1300 its season-ending bath. 

The directions recommend using two dirt guards – one in a soapy water (wash) bucket and another in a clean water (rinse) bucket. Since I just had one, I decided to use it in my soapy water bucket. This made it a little more difficult to get videos of the results, as I had to wait for the thick top layer of bubbles to dissipate.

I ride in the rain with some frequency, and I don’t bathe my motorcycle often – which meant the dirt guard had its work cut out for it. Rain water takes some dirt and grime off my bike, but there’s still some dirt and stickier road grime that gets just about baked onto the frame, engine and bodywork. I rode almost 20,000 miles in 2023 and washed the bike just once before the end of the riding season.

After giving the bike a thorough scrubdown, I waited for the bubbly top layer to go away and checked the water. It was a little foggy but pretty ok for how much dirt I’d just scrubbed off my motorcycle. I doubted whether something so simple and cheap could really be holding very much below it.

I reached into the bucket, lifted the dirt guard out, and the water turned a dark shade of bluish-black. I was very surprised how well the passive contraption had worked, and – though my jet-black motorcycle looked clean as usual after a bath – how much grime the dirt guard had obviously kept out of my sponge. 

My girlfriend was my videographer for when I pulled the dirt guard out of the bucket, and she suggested putting the dirt guard back into the bucket to see what happened. Since the dirt under the guard had been released when I removed it, I doubted the product worked so well that it would recapture all that floating grime. 

I was proven wrong. As the guard descended in the filthy water, it recollected the dark-colored water and left only the mildly hazy water that had previously occupied the space above it. I was seriously impressed.

It’s the middle of a northeast Ohio winter right now, but when it gets warmer out I’ll definitely be buying a second one come springtime. I don’t think I’ve found a product that exceeded my expectations as much as the Grant’s-brand Auto Detailing Dirt Guard has. For $5.99 (at press time), this product is easily worth it.