Woolwax vs Fluid Film | Honest Comparison

Are you upset about the underbody rusting of your car? Are you confused about which underbody coating should you use in your car? Woolwax or Fluid Film?

We will talk about all the benefits of Woolwax and Fluid Film in-depth and compare which of these undercoatings is better for you.

The major difference between them is that Woolwax is a thicker product than Fluid Film so it holds on longer. Also, Fluid Film tends to melt and drip when it is very hot which makes it less efficient and it had to be applied more frequently as compared to Woolwax.

Woolwax is more expensive than Fluid Film as it has more Lanolin content and hence is thicker than Fluid Film.

Both are Lanolin-based products. Lanolin or Wool-grease is a substance that mitigates rusting. They can be used for all types of conditions except for extremely hot areas as Lanolin gets burnt under excessive heat.

Note: Undercoating substances such as Woolwax and Fluid Film are not supposed to remove existing rust from the metal. These are used just to prevent the metal parts from further rusting.


WoolwaxFluid Film
ThicknessVery thickThick
ApplicationLess easy to applyEasy to apply
SmellAlmost odorlessMild odor
ColorClear and BlackClear and Black


Need for undercoating:

The underbody of your car is the most prone area to get rusted. This is because it is closest to the road and continuous chipping removes the paint of the underbody. Once the paint is removed, the metal catches rusting easily. Woolwax and Fluid Film protects your car’s underbody as these are a thick lanolin-based coating that prevents rusting.


Comparison between Woolwax and Fluid Film


Differences You Can’t Ignore:

  • Longevity: Although Woolwax and Fluid Film are both good products and many people have shown their trust in them over the years. However, Woolwax can withstand more road debris because it contains more lanolin or wool-grease as compared to other knock-off products such as Fluid Film. More Lanolin content means more thickness and more thickness means better wash-off resistance. It is an excellent corrosion inhibitor and therefore helps keep the underbody safe from corrosion for around one year after which you have to re-spray it.
  • Thickness: Woolwax has more lanolin or wool-grease content as compared to Fluid Film; hence it is thicker in consistency than Fluid Film. More thickness results in better longevity and wash-off resistance so whether you travel on-road or off-road, Woolwax will perform better and provide more protection as compared to Fluid Film.
  • Application: Both Woolwax and Fluid Film are not difficult to apply but when comparing them, Fluid Film is easier to apply as it is a spray-on product with little or no preparation. Although Woolwax can be applied as a spray-on, it is recommended that you should use an air gun for the best application results. Woolwax may need to be warmed up in front of a heater in cold weather before applying.
  • Smell: Woolwax has almost no smell (very little noticeable smell), but Fluid Film has a distinguished mild odor. It depends on the different individuals whether they prefer the smell of Woolwax or Fluid Film.
    In most cases, the smell dissipates after a week or so, after which you may feel the smell only once in a while. Therefore, the smell of either of them is less likely to be a deal-breaker for its potential customers.
  • Cost: The cost of Woolwax is more than Fluid Film, but considering its longevity, it is worth it. Fluid Film is not much inexpensive though, it is generally costlier than its other knock-off products.


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  • Reliability: Woolwax and Fluid Film are the products that are used by people for decades and have proven their credibility by providing unmatchable wash-off resistance and underbody protection to our vehicles.
    It is difficult to give an edge to one of the two over the other as they both are almost equally known and sophisticated products. It is sure that you will not regret the decision to choose any of the above products. The only thing that you should consider before buying them is whose smell is more acceptable to you.
  • Color: Both Woolwax and Fluid Film come in 2 colors: clear (straw) and black. Both colors have their distinct advantage apart from the color preference.If you have existing rust spots on the underbody of your vehicle, then you should go for black as it successfully hides the rust spots. One more advantage of black is that it is clearly visible. Therefore, when there is a wash-off at a specific part, you can easily re-spray that part without any hassle.On the other hand, clear is difficult to spot as it is not easily identifiable. If you want your vehicle’s underbody to look just like when it was brand new, you should prefer clear over black.
  • Self-healing: Self-healing means that if any small stone or road debris removes any part of the coating (Woolwax or Fluid Film), then it automatically will cover that part and repair itself.


Some Important Differences And FAQs:


Woolwax Clear vs black

Woolwax clear and black has the same application and purpose. The only thing that is different is their color.

Woolwax Black should be used by those who want to hide their car’s existing rust spots. One more use of Woolwax Black is that when it is wash-off from the underbody over the years, it is easy to identify that patch and cover it up.

Woolwax Clear is preferred by people who like their underbody in OEM (Original Equipment Manufacturer) color so the look and feel of it do not change.


Woolwax undercoating vs Fluid Film

The major difference between them is the thickness. Woolwax is considerably thicker than Fluid Film which results in better longevity and less frequent applications. Apart from this, Woolwax has almost no smell but Fluid Film has a distinguishing smell.

Pro-Tip: If your vehicle usage is only in the city and highways and you have limited running, it is better to save some bucks and go for Fluid Film.



What is better than Fluid Film?

If compared with other lanolin-based underbody coatings, Woolwax is better than Fluid Film. This is because Woolwax is thicker and can stay longer than Fluid Film therefore there are fewer chances of Woolwax being scraped or removed as compared to Fluid Film.

On the other hand, Fluid Film is more affordable than Woolwax, so you have to pay for the better longevity of Woolwax. In the end, it all depends on your needs.


Is Fluid Film worth it?

It is said that a Fluid Film is a reliable option when it comes to underbody coating. Its manufacturer claims that it can last for 36 months but it can chip off due to pebbles or other road debris easily. So, it is recommended to spray Fluid Film once every year.

Particularly, if you go off-road frequently, you should check the underbody every once in a while, to ensure that the coating has not been removed from any parts.

After all the above is ensured, it can be said that Fluid Film is worth it. Though there are other cheaper alternatives in the market, it offers better reliability. At the same time, it is more affordable than Woolwax.


How long does Woolwax last?

Woolwax claims that its shelf life is indefinite, it does not get expired. However, after application, you should re-apply Woolwax once every year to ensure it properly covers the underbody without leaving any parts. There are no solvents present in Woolwax therefore nothing can be evaporated.

It can be difficult to reach some parts of the underbody but once you manage to put the coating on them, they typically retain it longer as they are probably hidden from road debris better and hence remain protected. Woolwax claims that a single treatment to such protected enclosed areas can provide protection to the underbody for many years.


How long does waxed cotton last?

Waxed cotton is cotton that is treated with paraffin or natural beeswax that is applied to clothes. This process makes the cloth water-resistant and so it is used in making water-resistant clothes such as jackets and hats.

When used with the precautions that it comes with, Waxed cotton can last up to many decades. The precautions are that it should not be machine washed or dry cleaned, also it should not be washed with hot water or harsh detergents to keep its water-resisting quality intact.


How long does Fluid Film last?

The manufacturer of Fluid Film claims that Fluid Film can last up to 36 months after which it has to be re-sprayed. However, it is recommended to check annually and the treatment should be done in the parts where the coating has been removed because of road-wash, etc.


Does Fluid Film wash off?

Generally, Fluid Film is resistant to wash-off. But it can last up to a year without any issues after which it is recommended that you a look at the underbody and see if some of it has washed off.

There are 2 exceptions in this regard that you should keep in mind:

  • Since Lanolin is a heat-sensitive substance and it responds almost instantly to heat, it would simply burn in extremely hot conditions.
  • High-pressure washing of the vehicle’s underbody is not recommended especially during the winter season, as it may wash off the coating.


Does Fluid Film neutralize salt?

No, Fluid Film does not neutralize salt, rather you should Fluid Film the underbody if there is salt deposited in it as Fluid Film activates the salt which may result in totally defeating its purpose. It has been noticed that applying Fluid Film to salt-deposited parts got rusted pretty quickly.


Is Fluid Film safe on rubber?

If the rubber is non-oil resistant, it may cause swelling in it and hence damaging the rubber. On the flip side, if the rubber is oil resistant, it has no deteriorating effects on the rubber.


Will Woolwax stop existing rust?

Woolwax will not stop or remove existing rust. It is used to inhibit further rusting and corrosion.

If you want to hide the rust, the best solution is to use Woolwax black.


Will Fluid Film stop existing rust?

No, Fluid Film will not stop or remove existing rust but it will only prevent the treated part from further corrosion and rusting.

You should use Fluid Film black if you want to hide the existing rust.



Woolwax and Fluid Film are one of the most prominent corrosion and rust inhibitors in the market. They have displayed good wash-off resistance and hence are very credible among the people. If you want good all-around rust protection at a decent price, go for Fluid Film but if you want even better wash-off resistance and better longevity, you should go for Woolwax.

Woolwax is a bit expensive but it is better suited to people who have more off-road applications. For regular use, both of the products are pretty much evenly matched. The smell of each product is one factor you should consider before buying any of the 2 products.

You may go for any of them as they both boast of good reliability, customer assistance, and almost ubiquitous presence over the country. Hence, it is a given that you will not regret your decision to use either Woolwax or Fluid Film.