Even though one is certainly able to use dish soap to wash a car, one should never use dish soap as it is not specifically formulated to do so, and severe damage could result.
The gentlest dish soaps available should not even be considered when planning a vehicle wash. There is much that falls under the formulation of dish soap that prevents it from being a viable car washing option including its chemical makeup, purpose, and molecular structure.
Reasons People Think Dish Soap is a Good Idea
As established, dish soap should never be used to wash your vehicle, but there are reasons this question even comes up, and there are many reasons many people believe it is acceptable.
Pricing affects so many manufacturers and consumer decisions across all industries, and it often affects purchasing decisions when it comes to washing a vehicle.
Dish soap can usually be found at cheaper prices per ounce than vehicle soaps and shampoos, especially when it is a combination of a wash and wax.
The least expensive dish soaps can undercut the least expensive car wash soaps by five dollars or more per bottle. Even the more expensive dish soaps can be a dollar or two less than a comparably-sized bottle of car wash liquid.
The availability of a given product also plays a big role in its allure to customers. Most people going to any retail location will be able to find dishwashing soap more easily than car washing liquid.
Though many of the smallest grocery stores and gas stations still stock some quantity of car wash soap, selections are usually still very limited compared to dish soap, hand soap, and laundry detergent.
Additionally, and as a result of this, consumers usually have a much wider variety of dish soap types, scents, and brands from which to choose, making dish soap an easy choice over an often more expensive and limited car soap alternative.
What Makes Dish Soap a Bad Car Wash Shampoo Alternative?
It can be easy to justify buying a cheaper, more readily available type of soap that appears to do the same thing as a more expensive, specifically-designed type of soap for which you might have to go out of your way to find.
This may be the case at a surface level, but the implications and reasons car wash soap is better for your vehicle than dish soap are quite simple to understand.
Differing pH Levels
Dish detergents and soaps have a much wider range of pH levels than car wash soaps. The level of acidity or alkalinity – how basic it is – a substance has is called its pH level.
Car washing liquid can indeed vary in its pH levels, but it does not stray very far from having a neutral pH level as much as dishwashing soaps. Car washing soaps usually have pH levels from about 6.5 – slightly acidic – to about 7.5 – slightly basic. Dishwashing soaps and detergents can vary from 3 to 10 in the most extreme cases.
More often than not, dish soaps tend to be basic rather than acidic with average levels closer to 8. Some natural dish soaps can have the same neutral pH characteristics as car wash soap, but other things make dish wash soaps less than ideal for washing a vehicle.
One of the reasons dish soap is effective for washing grease away is that it is microscopically abrasive, even though it feels slippery to the touch.
Car wash soaps add additional lubricants to make it slide over the surface of your vehicle’s paint much more easily than a dishwashing soap would. Most car wash soaps are also designed to lather much easier and generate more suds to aid even further in its greater lubricity – the level of “slipperiness” a substance has – than dishwashing liquid.
Their minimal abrasion qualities are the same reason that microfiber cloths are used to wash vehicles instead of paper towels and sponges that both have rougher surfaces.
Not Specifically Formulated for Vehicle Paint
Even though dishwashing liquid and car wash soaps are both used for cleaning, they are both formulated for specific purposes, and as such, car washing liquids contain chemicals and additional substances that dish soaps do not.
Silicone, lubricating agents, waxes, and other polymers are common in car wash detergents beyond the simple cleaning agents. A similar comparison would be painter’s tape and duct tape, both of which are types of tape but are designed and used for different purposes.
Having seen all of these differences so far, the use of dish wash soap as a consistent alternative to dedicated car wash soap can cause a large amount of damage to both your vehicle’s paint and your wallet.
It is recommended to avoid washing your car too much, even with car wash soap, but using dish wash soap will both exacerbate any current paintwork damage or cause the paint to wear faster than it would under normal conditions.
Once one or both of these things happen, corrective measures will need to be taken so that your vehicle does not become damaged beyond the paintwork. Fixing paintwork can be expensive as the worst-case-scenario is a complete vehicle re-paint, a job that can cost thousands of dollars.
What Can Happen if You Use Dish Soap to Wash Your Car?
The three most common side effects of using dishwashing soap instead of car washing liquid are scratching, fading, and oxidation.
The use of dishwashing soap will begin to eat away at the clear coat of your vehicle because of both the decreased lubricity in dish wash soap and the grease-fighting formulas that tend to be harsher than those in car wash soaps. This might not be noticeable to begin, but it starts an accelerated chain reaction if not immediately addressed.
The second stage consequences of using dishwashing soap to wash your car include the acceleration of paint fading and oxidation levels. Even though paint fading and oxidation may not be readily apparent after the first time using dish soap, your vehicle’s paint may start to fade prematurely after only two or three years as opposed to ten, especially if you consistently use dish soap over car washing liquid.
The worst and final stages of damage are complete paintwork deterioration. This requires serious corrective measures including having the vehicle completely repainted. If taken even further, rust can occur on bodywork where paint has completely deteriorated.
Is There Any Time That is Acceptable to Use Dish Soap on a Vehicle?
In short, no.
In some specific instances, dish soap is used to strip a vehicle of a protective wax layer, usually to fix a paint issue or re-polish the vehicle, but this is rare as there are other more effective ways of completing this kind of task.
Dishwashing soap should never be used in place of a dedicated car wash shampoo. Car washing liquid is specially formulated to be gentle on a vehicle’s delicate paintwork and includes additives that can even keep the paint healthy.
Dishwashing soap does not have the same lubricating properties and is more abrasive, both of which lead to paint scratching, accelerated fading, and premature oxidation. In worst-case-scenarios, the consistent use of dishwashing soap over car wash soap can lead to complete paintwork deterioration and necessitate a complete vehicle repaint.