1. The right choice of performance properties of the oil. We choose oils with classifications and tolerances recommended for this car model. At the same time, you should not choose oils with the minimum allowable requirements (what they are according to SAE, API). It is better to dwell on oils of the latest classifications, in the worst case (with limited financial resources) – on “middle oils” (what they are according to SAE, API). Although they are inferior in quality to the latest engine oils, their properties are still higher than those of oils with minimum acceptable performance requirements (which they are according to SAE, API). And it is categorically impossible to choose oils with obviously inappropriate, understated indicators and tolerances. This statement is also confirmed in the new catalogs for the use of motor oils. Pay attention to the fact that in the latest catalogs there are still models of cars from very old years of production, but you will no longer find engine oils with old classifications, for example, with the API SF / CC classification. Therefore, for “veteran cars”, it is better to use oils of more recent developments and classifications.
However, there are exceptions to every rule. There are restrictions on the use of some modern oils in cars of earlier models. First of all, this applies to oils with reduced high temperature shear viscosity (HTHS – High Temperature High Shear). In new models of some vehicles, low viscosity oils (HTHS<3.5 mPa.s.) are recommended to reduce fuel consumption, and the engine design is specifically designed for the use of these special low viscosity oils. But the use of such energy-saving oil in cars of earlier years of production can lead to disruption of the normal operation of the engine up to its failure. This rule applies to oils with the following classifications and approvals: ACEA A1 / B1, A5 / B5, ACEA C1, C2; VW 503.00/506.00/506.01; BMW LL-01FE (Longlife Oil-01FE); Ford 913 A/B or special instructions for reduced dynamic viscosity HTHS. Oils with these specifications are not suitable for old cars.
2. Choosing the Right Engine Oil Viscosity. As mentioned above, the viscosity of the oil is determined by the operating conditions of the car and its condition. It is the second criterion that becomes decisive when choosing an oil viscosity for used cars. You should also remember and take into account problems during engine operation – waste, oil pressure, etc. If such violations are not observed, there are no restrictions on the choice of oil viscosity. In this case, you can only be guided by the climatic conditions of the car and your own wallet. To date, the optimum viscosity for all-weather use, energy saving, low-temperature and high-temperature parameters is an oil with a viscosity of SAE 5W-30. For Japanese and American cars, regardless of the year of manufacture and age, this viscosity is still optimal. A cheaper alternative for such vehicles may be 10W-30 viscosity oil. But for European hard-working cars, it is better to use oils with a viscosity of SAE 5W-40 or 10W-40.
3. If there are any deviations from the normal operation of the engine, special attention should be paid to the choice of viscosity. First of all, low-viscosity and energy-saving oils should be abandoned. Their reduced low-temperature, and in some cases, high-temperature viscosity can only exacerbate existing problems, because under conditions of engine wear and violation of its operating modes, the resulting protective oil film becomes thinner, less durable and no longer provides reliable protection of surfaces from wear and damage. In addition, low-viscosity oils have a higher volatility. This increases the loss of oil for waste and contributes to its even greater consumption. That is, in such problematic cases, oils with a higher viscosity at operating temperatures are required. And oils with viscosities 5W-50, 10W-50, 10W-60 come to the fore, 15W-50, 20W-50. But at the same time, when determining the viscosity, one should not forget about the performance properties of the oil. Only a competent combination of viscosity and oil specifications will extend the life of even a worn engine and delay its overhaul.