Many motorcyclists harm their machine with well-meant chemicals. The wrong can on the wrong part will cost you money, performance and, in the worst case, safety in the long run. Here are the 11 most common mistakes people make when using chemicals on their 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 watches their money, chemicals are one of the most important tools of all. They decide whether a seal lasts ten years or becomes brittle after an afternoon. And whether a bolt comes out cleanly or snaps at the first hard pull.
Here we clear up myths that have persisted in motorcycle forums for decades. And we don't just explain what you should buy, but also why some products protect your machine 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. The name stands for "Water Displacement, 40th formula", the 40th attempt to develop a water-displacing product. And that's exactly what it is: corrosion protection by displacing moisture. Trouble starts as soon as WD-40 is used as a lubricant.
WD-40 consists largely of cleaning solvents and volatile components. If you spray it on a squeaking chain, the noise disappears at first, because the thin liquid 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 parts have evaporated, hardly any lubricating film is left, and the original grease is gone anyway. The result: metal rubs on metal, and wear increases sharply. So remember: WD-40 is a cleaner and short-term rust loosener, but not a lasting lubricant for moving parts.
2. Brake cleaner: powerful, but not for everything
In many workshops, brake cleaner is something of an addiction. Spray it on once, and everything is 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 brake discs and pads so the friction values are right.
What many underestimate is the effect on plastics and rubber. A careless splash on the brake calliper can attack the sensitive dust boots of the brake pistons. The chemicals draw the plasticisers out of the rubber, and over time it becomes brittle and cracked. If moisture then gets 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 endure the most on a motorcycle. Dirt, heat and high centrifugal forces come together here. Classic white chain spray is the standard but has a clear disadvantage: 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 motorcycle stays clean, and the chain looks new for a long time. The catch: dry lube offers hardly any protection against rain. If you commute in all weathers, you'll quickly get surface rust on the chain plates with dry lubricant.
So you have to weigh it up: cleanliness and looks (dry lube) or the best wear protection in the wet (adhesive grease). A tip that costs little: clean the chain regularly with a soft brush and chain cleaner before re-lubricating. Fresh grease on old dirt is the surest way to ruin the chain kit prematurely.
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 preserves the resale value. One product has almost cult status in the scene: ACF-50. It was originally developed for aviation to protect aircraft on aircraft carriers from salt water. The liquid creeps into gaps and displaces moisture there.
Unlike wax, which forms a hard layer (under which rust often continues unnoticed), ACF-50 stays "active". It forms a thin, non-greasy film that closes again over small scratches. If you spray your motorcycle with it before winter (except brakes and tyres), you can simply rinse off the salt in spring and find it in very good condition underneath. You usually get the money back several times over when you sell.
5. Copper paste, ceramic paste and threadlocker
Hardly anything is as annoying as a snapped bolt. To prevent this, 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 spray water form a galvanic cell. The result is contact corrosion, and the bolt literally seizes in the aluminium block.
Ceramic paste is better here. It's metal-free, very heat-resistant and compatible with aluminium. It belongs on every spark plug thread and every axle. At the other end is threadlocker (e.g. Loctite). A common mistake: using "high strength" (green/red) where "medium strength" (blue) would be enough. High-strength threadlocker can often only be loosened by heating it to over 200 °C. At that temperature, nearby plastic parts and seals melt. The rule of thumb: blue for everything that vibrates. 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. If 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 strip the wafer-thin protective layer that protects the contacts from new corrosion. In the short term everything works again. In the long term, however, the pins corrode faster than before.
If you want lasting peace in the electrics, work in two steps:
- first clean to remove oxide and dirt
- then apply a touch of contact grease or terminal grease
This creates an invisible barrier against moisture and salt. The same applies to the electrics as to the engine: cleaning is only the beginning. The aftercare 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 can't be seen:
- water is forced into connectors
- moisture migrates into bearings and cables
- grease is washed out
- corrosion begins unnoticed
On top of that come many engine cleaners themselves. They contain surfactants and solvents that attack aluminium and remove protective layers. Weeks later, dull spots, white oxide stains 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
- don't use high pressure
- use mild motorcycle cleaners
- ride it dry afterwards
- treat sensitive areas with corrosion protection
Old mechanic's wisdom: a slightly dirty engine often ages more slowly than a clinically clean one.
8. Fuel additives: useful or money down the drain?
The shelf of fuel additives is full: cleaners, boosters, stabilisers, system care. Every little bottle promises more power and a longer engine life. The 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:
- during long periods of storage, to stabilise the fuel
- in old carburettor engines against gumming
- with 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'll save money and won't have 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 little sealant, a bit more just to be safe, and the problem seems solved. In fact, this is often where a chain reaction begins that ends in engine damage months later.
The sequence is simple:
- silicone oozes inwards
- excess pieces break off
- particles travel with the oil
- oil passages and strainers clog up
Modern engines are designed for precisely specified sealants. Anaerobic flange sealants only cure where there's no oxygen, i.e. exactly in the joint. What oozes out stays soft and does no harm.
This shows particularly clearly: it's not about quantity, but about 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 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 creep up:
- the lever feels spongy
- 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 with the wrong one just once, and the whole brake system can be ruined.
That's why:
- change brake fluid 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.
11. "More helps more": the most dangerous workshop myth
One of the biggest fallacies when working on bikes: more chemicals equal 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
Can I use engine oil for chain care?
In theory yes, oil lubricates very well. In practice, however, centrifugal force immediately flings the oil off the chain onto the rim and, dangerously, onto the rear tyre. Chain greases contain tackifiers that prevent exactly that.
Why does brake cleaner harm my O-ring chain?
The O-rings keep the grease in the chain pins. Brake cleaner is so thin and aggressive that it creeps under the seals and dissolves the grease. The chain then runs dry inside, which can lead to overheating and, in the worst case, a snapped chain.
What's the difference between rust remover and penetrating oil?
A rust remover often contains acids or other agents that break down iron oxide (rust). A penetrating oil (such as Ballistol or WD-40) is mainly meant to flow into the tiniest gaps thanks to very low surface tension. A good rust remover is usually also a penetrating oil, but not every penetrating oil dissolves rust effectively.
Is silicone spray good for tyre care?
Absolutely not. Silicone spray makes surfaces extremely slippery. If even a mist of it gets onto the tread, you lose a massive amount of grip. Silicone spray is, however, good for making brittle rubber hoses and plastic panels supple and shiny again.