The right motor oil for vehicle and machine

Motor oil does more than lubricate. It handles four jobs at once: it keeps apart metal surfaces moving against each other hundreds of times a second; it carries heat away from places no coolant reaches, such as piston crowns and bearings; it holds soot and wear particles in suspension and carries them to the oil filter; and it seals the gap between piston ring and cylinder wall, which is what compression and oil consumption depend on. That is why oil ages even when the vehicle is barely driven. Fuel and condensation get into the oil at every cold start, additives are used up, and viscosity shifts under shear. An oil that no longer does its job rarely announces itself straight away - it shows up later as rising consumption, a noisier engine, or worn camshafts and chain tensioners.

There are two systems for the interval. With a fixed interval, the figure in the owner's manual applies, usually a mileage limit and 12 months - whichever comes first. The flexible longlife interval is calculated by the vehicle itself from driving profile, oil volume and temperature, but it requires an oil approved for it. The 12 months are what most people overlook: a car covering 6,000 kilometres a year needs the same change as one covering 15,000, because condensation and fuel dilution depend on time, not distance. Anyone driving mostly short trips should change earlier under either system. A change includes a new oil filter and a new sealing ring for the drain plug. Fill about half a litre short of the nominal quantity, run the engine briefly and top up at the dipstick - the filter fills up, and the level drops once more after the first drive.

By base oil, oils are fully synthetic, semi-synthetic or mineral. Fully synthetic oils are built up deliberately rather than merely refined: they stay fluid in the cold, resist shear in the heat and age more slowly - every longlife approval and every low-ash oil belongs here. Semi-synthetics are the compromise for older engines; mineral monogrades are today a matter for classic cars and garden equipment. By viscosity, the SAE grade states how thin the oil is at a cold start and how load-bearing it is at 100 °C: 5W-30 is the most common grade for cars from around the year 2000, 5W-40 covers higher thermal loads, 10W-40 older high-mileage engines, 0W-20 modern hybrids. The third distinction, often overlooked, is ash content. Vehicles with a particulate filter need low-SAPS oil (ACEA C3 and related classes); a classic A3/B4 oil of the same viscosity will clog the filter.

In this order: approval first, then viscosity, then price. The approval is in the owner's manual and has to be found again on the container - if it only says "corresponds to" or "meets the requirements of", the oil maker has declared suitability itself and the vehicle manufacturer has not tested it. The quickest route is the oil finder: pick make, model and engine, and you see only the oils approved for exactly that engine. If you already know your approval, filter by it directly - VW 504 00/507 00 or BMW Longlife-04, say. The brand comes into it only after that, and then over price and pack size. A cheaper oil with the right approval is always preferable to a dearer one without it.

If you change oil for a living, you work in price per litre. The 20 litre canister is the quiet winner there: clearly cheaper per litre than a 5 litre pack, yet still an ordinary parcel with no freight forwarder and no delivery slot. From about one oil change a day, a drum starts to pay. The 60 litre drum covers around twelve changes and the 208 litre drum around forty; both arrive on a pallet by freight, with the slot agreed by phone. See engine oil in drums for all sizes, or 5W-30 in drums for the most requested viscosity. For workshops, tyre services, fleets and agriculture we quote net prices, volume pricing and freight for your postcode on request.

Used oil is hazardous waste. It must not go into household rubbish, into the drains or into the environment, and it must not be mixed with other substances - mixed used oil costs more to dispose of and falls outside free take-back. We take back free of charge the quantity of engine and gear oil bought from us, including the oil filter and the oily waste produced during the change. The details are under used oil disposal; this is not goodwill but every dealer's duty under section 8 of the German Used Oil Ordinance. Two things help the environment more than any label: the right oil and the right moment. An approved longlife oil in an engine designed for it means fewer oil changes over the vehicle's life, and a particulate filter stays intact only with low-ash oil - both save material, not just money.