Picking the Right Engine Oil

Engine oil, just like fuel, is sometimes of poor quality. Most often, counterfeits try to reach the market disguised as well-known brands such as Shell, Castrol, TNK-BP, “LUKOIL.” To protect yourself as much as possible from buying bad oil, try not to buy it in dubious places. Poor-quality oil most often turns up at sketchy kiosks, at markets, or sold hand to hand. Cases of counterfeit oil also crop up in large hypermarkets. You can find fully genuine oil at a brand-name filling station. In any case, one of the best options for Audi cars, especially with TDI diesel engines, is original VAG engine oil.

If you urgently need an oil change, try to hold out until you reach a filling station. If that's not an option, pick a less well-known brand, such as Motul or Liqui Moly. The less well-known the oil brand, the lower the chance it's counterfeit. It doesn't hurt to keep the receipt and the canister's labelling until the next oil change. Most importantly, after topping up a diesel engine with oil like this, you absolutely must swap it for a proper oil recommended by specialist Audi and Volkswagen service centres.

There are special designations used for labelling engine oils. Let's break down what they actually mean.

The most important marking on an oil label is the alternating numbers and letters, for example 10W-40. This is the ratio of the thickening index to viscosity under the SAE standard. The first number corresponds to the thickening index — the closer it is to 0, the lower the temperatures the oil can handle. Thickening indexes run from 0 to 15. The next number denotes the viscosity at an engine temperature of 100°C. So the higher this number, the thicker the oil. Viscosity values run from 30 to 60. The letter denotes the season the oil is meant for. W stands for WINTER, so this means it's a winter oil.

How do you work out which oil suits your car? The recommended oil parameters are always given in the car's manual. If you run into trouble starting the engine in winter, you need to use an oil with a lower thickening index. But it's not advisable to use an engine oil with a different viscosity. Higher oil viscosity can cause oil starvation, where oil pools up in the cylinder head.

The following letters denote the quality index under the API standard. The oil's quality is set by the second letter — the further along the alphabet it is, the higher the oil's quality. SF oil suits most Lada models and foreign cars from the 1980s, while SG oil suits more modern foreign cars.

To avoid wrecking your engine, you shouldn't use an oil, even a better one, that isn't intended for your particular car. Mineral oil is meant to boost the engine's wear resistance, while synthetic oils protect the engine from seizing up. If you decide to switch the engine from mineral to synthetic oil, you should flush the engine very thoroughly. You shouldn't skip flushing when switching to a semi-synthetic either.

An overly premium oil will do more harm than good to a car more than 5 years old.

There are times when you need to add oil urgently. For cases like this you should keep a one-litre pack with you, which a proper Audi service centre should give you specifically for topping up. If you don't have one, you should add an oil with the same indexes, or with a higher viscosity and quality rating under the API standard.