Chemicals on Your Motorcycle: 11 Common Workshop Mistakes

Many riders harm their bike with well-meant chemicals. The wrong can on the wrong part costs you money, performance and in the worst case safety in the long run. Here are the 11 most common mistakes made with chemicals on the motorcycle in the home workshop.

You know the smell in the garage: old oil, petrol and the pungent aroma of cleaning spray. For many, chemicals are just a means to an end. A bit of spray on the chain, a shot of penetrating oil on the seized bolt. But for anyone who works on their own bike and keeps an eye on money, chemicals are one of the most important tools there is. They decide whether a seal lasts ten years or goes brittle after one afternoon. And whether a bolt comes out cleanly or snaps at the first firm pull.

Here we clear up myths that have persisted in motorcycle forums for decades. And we don't just explain what to buy, but also why some products protect your bike and others slowly destroy it. So it's about lubrication, cleaning and corrosion protection, in a way that helps in practice.

1. WD-40: not a lubricant for moving parts

Hardly any product is as celebrated and at the same time as misused as WD-40. According to the manufacturer the name stands for "Water Displacement, 40th Formula", the 40th recipe for a water-displacing product. That's exactly what it is: corrosion protection by displacing moisture. Trouble starts as soon as WD-40 is used as a lubricant.

According to its safety data sheet, WD-40 consists mostly of thin hydrocarbons (solvents), plus a smaller proportion of mineral oil. If you spray it on a squeaking chain, the noise goes away at first because the thin stuff creeps into every gap. That's exactly the problem. WD-40 is a very good solvent. It gets under the grease in O-rings or bearings and literally washes out the permanent lubrication. Once the volatile components have evaporated, only a very thin oil film remains, and the original grease may be gone anyway. The result: metal rubs on metal, wear rises sharply. So remember: WD-40 is a cleaner and short-term rust remover, but not a permanent lubricant for moving parts.

2. Brake cleaner: powerful, but not for everything

In many workshops brake cleaner is something of an addiction. One spray and everything's clean and grease-free. But this aggressiveness has its price. Most brake cleaners are based on hydrocarbons that evaporate very quickly. The aim is a residue-free surface on discs and pads so the friction values are right.

What many underestimate is the effect on plastics and rubber. A careless splash on the caliper can attack the delicate dust boots of the brake pistons. Solvents can draw plasticisers out of rubber, which then becomes brittle and cracked over time. If moisture then gets in through the cracks, the pistons corrode, stick, and the brake overheats. So only use brake cleaner where metal meets metal. Cover rubber and painted parts around it or rinse them immediately with water.

3. Chain care: sticky chain spray or dry PTFE?

The chain has to take the most punishment on a motorcycle. Dirt, heat and high centrifugal forces come together here. The classic white chain spray is standard but has a clear drawback: it's sticky. That keeps the grease on the chain but also attracts road dirt and sand. This mixture acts like grinding paste on the sprockets.

A modern alternative is "dry lube" based on PTFE (Teflon). It forms a dry lubricating film to which hardly any dirt sticks. The bike stays clean and the chain looks new for a long time. The catch: dry lube hardly protects against rain. If you commute in all weathers, dry lubricant quickly leads to surface rust on the chain plates.

So you have to weigh it up: cleanliness and looks (dry lube) or the best wear protection in the wet (sticky grease). A tip that costs little: clean the chain regularly with a soft brush and chain cleaner before lubing again. Fresh grease on old dirt is the surest way to ruin the chain kit prematurely. More in Motorcycle chain maintenance.

4. Corrosion protection against salt and moisture

If you park your motorcycle on the street or ride all year round, you need good corrosion protection. It also maintains resale value. One product has almost cult status in the scene: ACF-50 from the Canadian manufacturer Lear Chemical. It was originally developed for aviation and is used there for corrosion protection of aircraft, including by the US military. The liquid creeps into gaps and displaces moisture there.

Unlike wax, which forms a hard layer (under which rust can continue unnoticed), ACF-50 stays "active" according to the manufacturer: it forms a thin film that remains able to creep and re-wets small spots. If you spray your bike with it before winter (excluding brakes and tyres), you can simply rinse off the salt in spring and usually find it in good condition underneath. A well-kept bike is also easier to sell later.

5. Copper paste, ceramic paste and threadlocker

Hardly anything is as annoying as a snapped bolt. To prevent it, professionals use anti-seize pastes. Classic copper paste is a perennial favourite, but should be used with caution on modern lightweight materials. Copper and aluminium together with splash water form a galvanic cell. The result is contact corrosion, and the bolt literally bakes into the aluminium block.

Ceramic paste is better here. It's metal-free, very heat-resistant and compatible with aluminium. Typical uses are exhaust bolts and header nuts. Not on spark plugs: NGK expressly advises against it because the paste acts like a lubricant, distorts the tightening torque by up to 20% and can damage the thread. The plug threads are coated at the factory. At the other end is threadlocker (e.g. Loctite). A common mistake: using "high strength" (red) where "medium strength" (blue) would be enough. According to its data sheet, high-strength threadlocker such as Loctite 271 can only be released by heating the joint to about 250 °C. At that temperature, nearby plastic parts and seals suffer. The rule of thumb: blue for everything that vibrates and should come undone again. Ceramic for everything that gets hot.

6. Contact cleaner: only the first step on the electrics

Modern motorcycles are computers on wheels. ABS, traction control, quickshifter and ride-by-wire only work as well as their connectors. When error messages appear or the engine stutters in the rain, attention quickly turns to the contacts, and reaching for contact cleaner is almost automatic.

But it's worth taking a closer look. Many cheap contact cleaners consist almost entirely of aggressive solvents. They reliably remove oxide and grease, but also remove the wafer-thin protective layer that protects the contacts from new corrosion. In the short term everything works again afterwards. In the long term, though, the pins corrode faster than before.

If you want lasting peace in the electrics, go in two steps:

• first clean, to remove oxide and dirt
• then apply a touch of contact grease or terminal grease

That creates an invisible barrier against moisture and salt. The same applies to the electrics as to the engine: cleaning is only the beginning. The after-treatment decides how long it lasts.

7. Engine washing: clean, but with side effects

A spotless engine looks reassuring. That's exactly the trap. The typical routine: cold engine, pressure washer, plenty of cleaner, lots of water. What happens out of sight isn't visible:

• water is forced into connectors
• moisture migrates into bearings and cables
• grease is washed out
• corrosion starts unnoticed

Add to that many engine cleaners themselves. They contain surfactants and solvents that attack aluminium and remove protective layers. Weeks later, dull patches, white oxide spots and the first rust spots appear, long after you've forgotten the wash.

If you want to clean the engine, do it like this:

• engine lukewarm, not cold
• no pressure washer
• use mild motorcycle cleaners
• then ride it dry
• treat sensitive areas with corrosion protection afterwards

Old mechanic's wisdom: a slightly dirty engine often ages more slowly than a clinically clean one.

8. Fuel additives: sensible or money down the drain?

The shelf of fuel additives is full: cleaners, boosters, stabilisers, system care. Every bottle promises more power and a longer engine life. Reality is more sober. Modern fuels already contain elaborate additive packages.

So many additives only duplicate what's already in the petrol. Additives only make sense in a few cases:

• for long periods standing, to stabilise the fuel
• for old carburettor engines against gumming
• for demonstrably dirty injectors

What additives can never do:

• repair mechanical wear
• heal worn bearings
• compensate for loss of compression

Chemicals can protect and clean. They can't repair. If you know that, you save money and don't raise false hopes.

9. Liquid gasket: too much of it harms the oil circuit

As soon as oil seeps somewhere, the silicone tube is ready. A bit of sealant, a bit more to be safe, and the problem seems solved. In fact, this often starts a chain reaction that ends months later with engine damage.

The process is simple:

• silicone squeezes inwards
• excess breaks off
• particles travel with the oil
• oil passages and strainers clog

Modern engines are built for precisely defined sealants. Anaerobic flange sealants only cure where there's no oxygen and metal contact, i.e. exactly in the joint. What squeezes out doesn't cure and therefore doesn't clog strainers with solid lumps. Still, only use what the manufacturer specifies for each point.

This shows particularly well: it's not the amount that matters, but the right product in the right place.

10. Brake fluid: underestimated high-performance chemistry

Brake and clutch fluid is one of the most aggressive fluids on a motorcycle and yet the one most often forgotten. It absorbs water from the air, attacks paint and loses a bit of its safety margin with every percent of moisture.

The consequences come gradually:

• the pressure point gets soft
• the boiling point drops
• vapour bubbles form
• braking performance collapses

It gets even more dangerous with the wrong type. Silicone-based DOT 5 can't be mixed with DOT 3, 4 or 5.1. Top up wrongly just once, and the whole brake system can be ruined.

So:

• change brake fluid according to the manufacturer, usually every 2 years
• only use the DOT type approved by the manufacturer
• always cover paint and plastic

Brake fluid doesn't age with kilometres, but with time. More in Checking motorcycle brakes.

11. "More is better": the most dangerous workshop myth

One of the biggest thinking errors when working on bikes: more chemicals means more protection. It's often exactly the opposite.

Too much lubricant:

• binds dirt
• insulates heat
• creeps into the brakes
• ends up on the tyres
• impairs function

Most products work best:

• as the thinnest film
• precisely dosed
• only where they're needed

Experienced mechanics don't work with a watering can but with a scalpel. Chemicals aren't a stopgap but a precision tool.

Frequently asked questions about chemicals in the motorcycle workshop

Sources

• Company history and origin of the name (WD-40 Company)
• WD-40: composition according to the safety data sheet (Wikipedia)
• History of Lear Chemical and ACF-50 (ACF-50 Europe)
• 5 Things You Should Know About Spark Plugs (NGK)
• Technical data sheet Loctite 271 (Henkel)

Last checked: September 2026. The manufacturer's information for your motorcycle takes priority.