Contents: The Many Talents of Multipurpose Oil ↳ High price - synthetic easy flow oils ↳ Read the fine print on the can ↳
At this point you should have no more doubts: oil is the elixir of life for your Focus engine. It reduces friction and wear on pistons, cylinders, and all bearing journals of the crank and valve train. In addition, engine oil provides a seal between the pistons and the cylinder walls. The gases that form during combustion, like an explosion, act on the crankshaft almost without losses thanks to the "oil sealant". This is far from exhausting the talents of engine oil: engine oil takes on a large part of the cooling of the interior of the engine. In addition, it protects against corrosion, keeps dirt particles in suspension and binds some of the chemical products of combustion.
The Many Talents of Multipurpose Oil
Modern motor oils are lubricants made from refined crude oil. But before they can begin their career as motor oil, manufacturers add special additives. At the end of the refining chain, this amounts to up to 20% of the motor 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 VI correctors (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 "adjust" the motor oil to the engine temperature. Skillfully mixed additives cover several viscosity classes at once. But VI correctors have the negative property of wearing out at high temperatures and therefore losing much of their effectiveness. In addition, water, fuel and combustion products set natural limits on the service life of motor oil. Liquid mineral oil cannot withstand the pressures and temperatures prevailing in the engine for a long time to a sufficient degree. Therefore, regular oil changes are not a luxury that can be abandoned, but a technical and chemical necessity - if the engine is to operate without problems.
High price - synthetic easy flow oils
In principle, synthetic oils are no more artificial than mineral oils, but they are considerably more expensive. The reason: during their production, the molecular structure of natural oil is destroyed by a labor-intensive method (cracking) and recreated using a new formula with special additives. As an equivalent to the high price, manufacturers promise reduced oil and fuel consumption, increased stability and longer durability: theoretically, this also means longer oil change intervals. If you want to have such a premium oil, you should not, however, excessively increase Ford's already very long oil change intervals.
Read the fine print on the can
A traditional multi-purpose oil is sufficient for the engine of your Ford Focus. The important thing is that the oil must meet the requirements of the relevant standards. If in doubt, consult your dealer, since the suitability of the oil is not determined by well-written advertising, but only by its specification, the required viscosity class and the small print on the can: Ford recommends SAE 5W-30 engine oils for the Focus, which must at least meet the ACEA Al/B 1 and WSS-M2C912-AI or WSS-M2C913 specifications (for diesel engines WSS-M2C913-A or WSS-M2C912A). If you use other oils, they must meet the API SH quality (for diesel engines CC MC G5, PD2, API SH). Oils with the designation API SC, SD, SE or SF (for diesel engines API CC) could even damage your Focus. If the oil meets the above criteria, oil grades from different manufacturers can be mixed. But you must take into account that the special qualities of the original formula are reduced. Each product has a special additive formula, the effectiveness of which may be reduced when mixed with other oils. For this reason, there is no point in combining mineral and synthetic oil. Just as you cannot mix pure diesel oils with petrol engine oils - in the worst case, you will thereby cause engine damage.
This is the right thing to do: Focus engines do not necessarily need to run on expensive synthetic oil. Ford recommends using SAE 5W-30 viscosity grade motor oils in our latitudes.