2020 test7 productsShop Chemicals & Lubricants
Which Corrosion Inhibitor Spray Brand Wins?
We compared 7 corrosion inhibitor spray options head to head. CRC Heavy Duty Corrosion Inhibitor came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Winner
CRC Heavy Duty Corrosion Inhibitor
Price shown in test: $12.60 for 10 ounces or $1.26 per ounce
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Runner-up
Flex Seal
Price shown in test: 92 cents per ounce or $12.89 for 14 ounces
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The measured results
Every number below is read straight from the test. Scroll sideways to see all measurements. Products are listed in the order they finished.
| Product | Dirt/dust road test | 24 hour oxidizer plus dirt/water test | 48 hour stationary test | Pressure washer survivability | 24 hour oxidizer test | 48 hour dirt/water test | Rusted panel test | 48 hour test |
|---|---|---|---|---|---|---|---|---|
| 1CRC Heavy Duty Corrosion Inhibitor$12.60 for 10 ounces or $1.26 per ounce | Flex Seal and CRC seem about the same. CRC may look like it has more dirt accumulation on it due to the color, but actually CRC turns into a dry surface and it just doesn't seem to be a magnet for dirt | CRC definitely seems like a first place finish with Flex Seal coming in a close second | CRC did an amazing job. I'm really impressed with how this product performs | I'm really impressed with CRC. It definitely did the best coming in first place. The high pressure washer did not remove the CRC from either metal panel | not tested | not tested | not tested | not tested |
| 2Flex Seal92 cents per ounce or $12.89 for 14 ounces | Flex Seal actually did a very good job. Not a whole lot of dirt accumulated on it | Flex Seal coming in a close second | Flex finished in second place just ahead of Fluid Film and just behind CRC | Flex Seal actually did very well. It survived the pressure washer and there is a little bit of rust that's formed where the rock chips occurred. In my opinion, a second place finish | not tested | not tested | not tested | not tested |
| 3WD-40 Specialist Long-Term Corrosion Inhibitor$1.68 per ounce or $10.89 for 6 and 1/2 ounces | WD-40 Long-Term Corrosion Inhibitor definitely seems to be about the same as used motor oil. Quite a bit of dirt collected on the panels | not tested | not tested | WD-40 actually did a better job than Fluid Film and Corrosion X withstanding the pressure washer... it did really seem to cause a lot of issues for WD-40 Specialist which finished third | WD-40 Rust Specialist is also doing a fantastic job. I don't even see rust where the hammer has come in contact with the steel | not tested | not tested | not tested |
| 4Fluid Film85 cents per ounce | Fluid Film definitely caused a lot more accumulation of dirt | not tested | not tested | the pressure washer seems to remove the Fluid Film from the clean metal panel. However, the panel that had Fluid Film on it that was already rusted is looking pretty good | Fluid Film just totally crushed it. It did a fantastic job at blocking the rust | Fluid Film fourth | not tested | not tested |
| 5Corrosion X HD$19.18 for 12 ounces, that's $1.60 per ounce | CorrosionX is definitely by far the worst. Look at that. That is a mess | not tested | not tested | the pressure washer seems to have washed away the Corrosion X protection | CorrosionX is actually doing a fantastic job so far in the testing. I don't see any corrosion forming where the CorrosionX has been applied | Corrosion X heavy duty third place | not tested | not tested |
| 6Corrosion Block$9.72 for just 4 ounces or $2.43 per ounce | not tested | not tested | not tested | It appears that the pressure washer removed the protective barrier provided by the Corrosion Block product | the Corrosion Blocker isn't blocking the rust. You can see quite a bit of rust beginning to form | Unfortunately, Corrosion Block isn't doing too well compared to some of these other brands. It is doing better than used motor oil as well as the control | not tested | not tested |
| 7Rotella T4 15W-40 used motor oil | not tested | not tested | not tested | not tested | it's just not going to do a very effective job. As you can see, it's definitely better than the control, but there's still a lot of surface rust that has already formed | not tested | for the metal that already had some rust pits it looks like used motor oil actually made the problem worse | I don't really see any benefit of used motor oil over the control. They look to be about the same |
How it was tested
- dirt and dust accumulation while driving on a gravel road
- simulated rock chip damage with a chipping hammer
- accelerated rusting via an oxidizer of hydrogen peroxide, vinegar, and salt over 24 and 48 hours
- high pressure washer survivability test
“I'm really impressed with CRC. It definitely did the best coming in first place.”
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