At Lohen we’re frequently asked about engine oils for MINIs; what’s best to use and why we use what we do. In this blog we’ll provide a basic understanding, insight into the jargon that surrounds engine oil and some advice on choosing the correct engine oil for your standard or modified MINI.

The function Of Engine Oil

Engine oil is required to lubricate engine components and to reduce friction, wear and heat build-up. In the MINI, especially the Generation 2 MINI, engine tolerances on critical components such as the camshaft and crankshaft are minute so it’s important to reduce wear by using a good quality and clean oil. Walnut shell is used to remove the coke build up on your Gen 2 MINI because it is a very gentle abrasive and does not damage or mark the engine components making it a safe and effective method of servicing.

Identifying Oil

You might be wondering: What type of oil is best for my MINI? Should I use synthetic or mineral engine oil in my MINI?

Synthetic and mineral engine oils are both made from crude oil. Mineral oil is refined from crude oil; synthetic oils are chemically altered changing their molecular structure. Synthetic oils are better for use in engines because they can be manufactured to have specific properties, be more stable and the molecular structure made more consistent, rather than the natural variations that are present in mineral oil. The additional processes and additives make synthetic oils more expensive. Semi-synthetic oils are a blend of mineral oil and synthetic and offer a compromise between performance and cost.

What do the markings on oil bottles mean?

Various institutions have devised quality and grading systems for engine oils. Some of the more relevant are as follows: European Automobile Manufacturers Association (ACEA) is a European body that, by working with oil producers, test houses and vehicle manufacturers, has defined a standard for engine oils. There are different grades within this standard that are suitable for different engine types. Briefly summarised, the ACEA categories are as follows: A/B - oils suitable for use in petrol and diesel engines C - catalyst compatible oils E - oils suitable for heavy-duty diesel engines Each category then has further grading levels and contains some cross over. The Society of Automotive Engineers (SAE) devised a method of characterising oils based on their viscosity, where a higher number denotes a more viscous oil. A ‘W’ usually follows the number. This denotes winter, not weight as commonly thought. This is important as it demonstrates the oils low-temperature viscosity; effectively how the oil behaves when you start up your MINI’s engine. Simply put, a 10W rated oil flows more easily than a 20W rated oil. Don’t be confused by the brand of oil; most brands and vehicle manufacturers have several different products or levels of oil. The important thing is to read the label carefully because, for example, some oils are branded to meet or exceed certain standards, look for the SAE rating and type i.e. fully synthetic, semi synthetic or mineral.

There are two numbers on the oil container, what do these mean?

When creating synthetic oils, engineers have created an oil that is thinner when cold and thicker when warm. This is shown in the oil labelling e.g. 5W30 this acts like 5W oil when tested at a given lower temperature and like 30W oil when tested at a given higher temperature. This seems backwards but considers engine operation; good circulation is required quickly when the engine starts in order to quickly coat engine components and prevent wear, while improved protection is achieved from the thicker oil as the engine gets warm.

Choosing the right oil for your MINI.

Fully Synthetic oil has a lower burn rate than conventional non-synthetic or semi-synthetic oils and this is significant with turbo engines like we see in the Generation 2 and 3 MINIs. Typically, synthetic oil has a significantly lower burn rate than conventional mineral oils. This means that the conventional oil will leave significantly more harmful deposits within the turbo over synthetic. It’s these deposits that eventually cause the wear that can lead to turbo replacement. Typical exhaust operating temperatures are around 480°c whilst oil burns at around 200°c. The shaft of the turbo “floats” in oil when the engine is running, when you turn off the engine, the engine no longer supplies oil to the turbo. The oil that is left in the feed pipe, and on the shaft, will begin to burn. This is the area where your synthetic oil really matters. It’s important to choose high quality synthetic oil for your MINI to maximise performance and life. The grade of oil depends upon usage. Lohen use fully synthetic Motul 8100 X-Clean 5W 30 oil in our all petrol, diesel, non or lightly modified MINIs. This does vary from MINI’s recommendations as it can reduce oil consumption and coking, where applicable. For more highly modified MINIs heavier higher quality oil is suggested. At Lohen we offer a couple of options; a Motul 8100 5w40 100% synthetic oil which is ideal for those tuning a road or track day MINI. If however you're seeking the best lubrication and heat resistant and don't mind changing the oil more frequently look no further than the famous Motul 300V engine oil, the 5W30 variant is perfect for the MINI and the oil of choice for hard circuit uses or those with highly modified MINIs.

Will using heavier weight oil have any adverse effects?

Modified MINI’s have power much greater than standard so the manufacturers' original recommendation is no longer applicable. For the 250+ BHP that a modified MINI runs we would suggest the Motul 8100 5W40. This will withstand higher temperatures than a 5W30; a 5w30, as opposed to a 5w40, will thin out quicker at the optimum high temperature. So if you have a 5W40 then this will not break down as quick thus giving extra protection to the engine. The quality and characteristics of the Motul 300V variant does through a slight curve to this, but it's also a more costly product that requires more frequent servicing intervals, making it less suitable to those runing a car on the road.

Will my MINI’s turbo wear quicker with heavier oil?

Circulating oil early in the running process is important to lubricate the turbo and other engine components, so this is an understandable question and concern. There’s no adverse effect on turbo life and wear despite Motul 5W40 being heavier oil.

Why is it important to change the engine oil regularly?

When heated repeatedly, oil degrades and produces sludge. This sludge, if left untreated, will slowly restrict the oil passageways within the engine, preventing the engine oil from circulating which can lead to severe engine damage.  Modern engine tolerances are so minute and operating pressures of oil pumps are limited to improve fuel economy and performance, for these reasons it is important to fully drain the old engine oil and replace it. An engine oil flush such as the Motul Engine Flush can also help to remove deposits and sludge. It’s worth considering adding this to your oil change service.

In order to maximise performance and limit engine wear on the MINI engine use synthetic oil. Lohen suggests using a 5W30 oil cross all petrol models running standard power or lightly modified. And, don't forget; you can remove all stress from choosing your MINI's oil by letting Lohen do it! We offer quality, affordable servicing for all MINI models check out the Servicing page under your vehicle for more information.

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