The wrong lubricant is worse than none at all

Treat the sections below as a sequence. With lubricant selection, getting the early decisions right makes the later ones much easier.

What a lubricant is made of

Grease consists of a base oil held in a thickener, and both components determine its behaviour under load and temperature. Additives provide extreme pressure performance, corrosion protection and oxidation resistance, and they are chosen for a specific application. Viscosity determines the film thickness at a given speed and load, and too thin a film allows metal contact while too thick wastes energy as heat.

Temperature range matters at both ends, since a grease that stiffens in cold will starve a bearing at start-up. These properties are published on data sheets, which are freely available and rarely consulted by owners.

Where the wrong choice does damage

Some oils and greases swell or dissolve particular plastics and elastomers, which destroys seals and bushings quickly. Mixing incompatible greases can cause the thickener systems to separate, releasing the oil and leaving a useless residue. A light penetrating oil applied to a bearing washes out the grease that was doing the work, leaving it effectively dry.

Silicone lubricants are excellent on rubber and plastic and are unsuitable where extreme pressure additives are required. Food-grade requirements apply to anything near food, and using an industrial product there is a contamination problem rather than a mechanical one.

Penetrating oil is not a lubricant

Penetrating fluids are formulated with low viscosity and solvents to creep into corroded threads and break the bond. They evaporate and leave little film, so a joint freed with penetrating fluid still needs a proper lubricant afterwards. Using them as general lubricants on hinges, chains and bearings produces a brief improvement followed by a worse condition.

This is one of the commonest domestic maintenance mistakes and is easy to avoid once the distinction is clear. Keeping both a penetrating fluid and an appropriate lubricant, and using each for its purpose, is the whole solution.

Where lubrication is not wanted

Some mechanisms are designed to run dry, using self-lubricating polymers that are ruined by oil attracting grit. Locks are frequently specified for dry lubricants, since oil collects dust and forms a paste inside the mechanism. Brake and clutch surfaces are contaminated by any lubricant, which is obvious and still happens through overspray.

The measurable part is this: sealed bearings are lubricated for life and adding grease externally achieves nothing while attracting contamination.

Reading the manual before lubricating anything is quicker than the repair that follows lubricating the wrong part.

Quantity and frequency

Overfilling a bearing with grease causes churning, which generates heat and can be worse than slight underfilling. Manufacturers specify quantities and intervals for equipment with grease points, and those figures come from testing. Chains and exposed mechanisms need cleaning before lubrication, since fresh oil over grit creates a grinding paste.

Excess lubricant attracts dust and forms deposits, which is why a clean, lightly lubricated mechanism outperforms a heavily greased one. Regular light maintenance is more effective than occasional heavy intervention across almost every category.

Finding the right product

The manual usually specifies a lubricant type or a standard designation rather than a brand, which is what to search for. Data sheets state compatibility with plastics and elastomers, temperature range and load capability. Where a manufacturer sells a specific lubricant, its data sheet reveals whether it is a genuinely special formulation or a repackaged standard product.

In the small print, trade suppliers and repair communities know which substitutes work in practice and are usually willing to say. This site does not test lubricants, so manufacturer specifications and technician experience are the sources to rely on.

The takeaway

Find out what the manual specifies before applying anything, because the wrong product removes the protection that was there.

Anything you cannot buy a spare part for is a rental with a long term.