Motor oil is a fluid with many talents

At this point, you should no longer doubt: oil is the elixir of life for your Focus engine. It reduces friction and wear of pistons, cylinders, as well as all bearing journals of the crank and valve mechanism. In addition, engine oil provides a seal between the pistons and cylinder walls. The gases produced during combustion are similar to an explosion, thanks to «oil sealant» act on the crankshaft almost without loss. This is far from exhausting the talents of engine oil: engine oil takes on most of the cooling of the inside of the engine. In addition, it protects against corrosion, holds dirt particles in suspension and binds some of the chemical products of combustion.

Numerous talents of multi-purpose oil

Modern motor oils are lubricants made from recycled petroleum. But before they can start their careers as motor oils, manufacturers will add more specialty additives to them. At the end of the recycling chain, this amounts to up to 20% of engine oil. Additives protect the oil, for example, from oxidation and prevent it from foaming at high engine speeds. One of the most important additives are correctors VI (VI = viscosity index). To clarify: VI correctors are long chains of molecules that swell when exposed to heat and shrink again when cooled. Thus, VI correctors automatically «set up» engine oil for engine temperature. Skillfully mixed additives cover several viscosity grades at once. But VI correctors have the negative property of wearing out at high temperatures and therefore losing most of their effectiveness. In addition, water, fuel, and combustion products place natural limits on engine oil durability. Liquid mineral oil cannot adequately withstand the pressures and temperatures prevailing in the engine for a long time. Therefore, regular oil changes are not a luxury that can be dispensed with, but a technical and chemical necessity if the engine is to run without problems.

High price - synthetic low-flow oils

In principle, synthetic oils are no more artificial than mineral oils, but are significantly more expensive. Reason: during their manufacture, the molecular structure of natural oil is destroyed by a laborious method (cracking) and according to the new recipe is again created with special additives. As the equivalent of a high price, manufacturers promise reduced oil and fuel consumption, increased stability and longer life: in theory, this also means extended oil change intervals. If you want to have such a superior quality oil, you should still not extend Ford's already very long oil change intervals beyond measure.

Read the fine print on the jar

For the engine of your Ford Focus, a traditional multipurpose oil is sufficient. It is important that the oil must meet the requirements of the relevant standards. In case of doubt, consult your dealer, as the question of the suitability of the oil is not decided by a well-made advertisement, but only by its specification, the desired viscosity grade and the text on the can printed in small print: Ford recommends SAE 5W-30 engine oils for Focus, which, as a minimum, must comply with ACEA Al/B 1 and WSS-M2C912-AI or WSS-M2C913 (for diesel engines WSS-M2C913-A or WSS-M2C912A). If you use other oils, they must be of API SH quality (for diesel engines SS MC G5, PD2, API SH). Oils with API designation SC, SD, SE or SF (for API CC diesels) might even damage your Focus. If the oil meets the above criteria, then oils from different manufacturers can be mixed with each other. But you must take into account the fact that the special qualities of the original recipe are reduced. Each product has a specific additive formulation that may be less effective when mixed with other oils. For this reason, there is no point in combining mineral and synthetic oil. Just as you should not mix pure diesel oils with oils for gasoline engines - in the worst case, you will provoke engine damage.



You're doing the right thing: Focus engines don't have to run on expensive synthetic oils. Ford recommends using SAE 5W-30 viscosity grade engine oils in our latitudes.