Engine Oil Myths Debunked: Thick Oil, Idling Warm-Ups and the Truth About Black Oil

The AutoClub episode puts word-of-mouth beliefs about motor oil on the table one by one. The program moves in a question-and-answer format, and the first question touches one of the most deep-rooted myths: the idea that old cars must always run on thick oil. The guest expert's answer shows the matter depends on engineering, not age. Thirty or forty years ago, 20W-50 grades were nearly the market standard, because engines designed in those years were built exactly for that fluidity. Small adjustments for climate were possible, but the production technology of the engine always decided.

Single-grade oils were also common in the same era; products known as number 30, number 40 or number 50 meant a different viscosity for winter and summer. Separate cans stood on the shelves for gasoline and diesel engines, and drivers changed oil with the season. Modern multigrade oils changed this order; grades such as 20W-50 brought a flexibility usable in both winter and summer. The point the program underlines is clear: the correct oil is decided not by the age of the car but by the technical specification set by the manufacturer.

The second big myth is the habit of warming the car at idle for minutes, especially on winter mornings. The expert rejects this belief firmly, because an engine warms up under load, not while standing still. After starting, a short wait of 10 to 20 seconds is seen as enough for lubrication to complete. Then, with a gentle start, early gear changes and avoiding high revs, the engine reaches its ideal working temperature quickly. Once the temperature returns to normal, the car can be driven as usual.

Aftermarket additives are also on the program's agenda. Since an oil matching the manufacturer's required specification already contains a complete additive package, top-up products are argued to be unnecessary. Likewise, darkening of the oil is not accepted as a standalone sign of a spent oil. Because detergent structures in modern oils keep dirt and soot suspended, the color can darken fast; the classic example cited is old diesel engines whose oil came out pitch black right after a change. Decisions should follow the change interval and the maker's conditions, not the color.

Oil consumption is surrounded by misunderstandings too. The program stresses that burning some oil does not always mean poor-quality oil; it is a natural process tied to the engine's inner design and mileage. Even at zero kilometres, makers accept a certain consumption as normal; the example recalled is a 1990s 1.6-litre carburetted model whose handbook allowed up to one litre per thousand kilometres. That figure sounds bold today, because change intervals of 5,000 to 7,500 kilometres in old engines have given way to talk of 20,000 kilometres now.

Oil described as thin as water, which mechanics test by rubbing it between their fingers, is defined as a genuine risk signal. An oil that has lost its fluidity control and grip can no longer protect the engine. More surprising is the garaged-car myth: the thought that never-used oil cannot degrade is wrong. Even an unopened can has a shelf life of about five years, and expired product must not be used. The program compares this to tyres and to houses left unused for years; like everything standing motionless, oil loses its properties over time.

The closing rule is summed up in one plain sentence: the maker's stated time or mileage, whichever comes first. One year or 20,000 kilometres is given as the typical value; yet for cars driven in constant stop-and-go traffic like Istanbul, an earlier change is advised without waiting for the limit. The same logic applies to warranty terms, where time and mileage count as alternatives. The warning is not limited to engine oil; neglecting unseen fluids such as transmission, hydraulic and coolant can also produce heavy repair bills. While every used-car buyer checks the paint, overlooking the mechanics becomes the program's most current warning. At the end, viewers are directed to a lubricant brand's technical support line for choosing the right oil for their cars.