Ask the Mechanic: What is the best engine oil for my VW Golf 1.2L TSI?

What you need to know:

Hello Paul, I own a 2015 VW Golf 1200cc TSI. What is the best engine oil for it; 5W-40 or 5W-30, mineral or synthetic? Also, the manufacturer recommends Castrol on the engine caps. Any issue with using other brands? Finally, it is now 158,000kms, at what point shall I switch to high mileage engine oils?


Hello Fred, the best engine oil for your VW Golf 1.2L TSI should meet the manufacturer recommended viscosity index or grade. To avoid any confusion, you must understand the difference between mineral or synthetic engine oils. Mineral-based engine oil is mostly from natural crude oil, drilled from the ground and refined with performance and protection enhancing additives. Synthetic-based engine oil is manmade oil blended and prepared with chemicals designed to provide superior engine performance and protection.

Synthetic (fully synthetic) oil meets the high demands and challenges of modern engines such as extreme heat or cold, internal combustive pressure, after burn soot and demand for fuel economy and long life. Therefore, synthetic and mineral-based oils are not the same nor should they be interchangeably used. There are semi-synthetic based engine oils which have mineral base oil blended with artificial additives to improve their engine performance and protection levels.

The viscosity indexes and performance or protection levels of these three types of engine oils are different. Viscosity is how easily and quickly engine oil will flow at different temperatures to protect your engine. When considering temperature ranges, the engine oil manufacturer declares the temperature ranges in which their oils will still flow.

The first digits denote the cold (-) temperature range while the second set denote the hot (+) range. For instance, 5W-40 engine oil will be able to flow in freezing subzero temperature while -35 degrees to +40 degrees in hot temperature.

In addition, different Synthetic, semi synthetic or mineral-based oils have performance grades or standards classified by the American Petroleum Institute (API) and European Association of Automobile manufacturers (ACEA).

All engine oils ought to subscribe, be tested and graded by the above internationally recognised standard. Car manufacturers design and test their engines to perform optimally using engine oils categorised by the temperature range, API and ACEA standards, which declare whether the oil is suitable for petrol (SP -Spark) or diesel (C - Compression) engines or both petrol and diesel (S/C).

Therefore, any reputable engine oil should have undergone tests which declare its viscosity, API and ACEA standard. VW, under their bulletin 502.00/505.00, recommend oil viscosity, API and ACEA which meets the tolerance levels of a range of their vehicle engines which include your 1.2 L TSI.

Different 5W-30 fully synthetic engine oils which meet and declare API SL/CF; ACEA A3/B3, A3/B4 are approved for your particular VW engine tolerance levels. Interestingly, the 5W-40 fully synthetic engine oil which has almost similar API and ACEA and can be a good alternative in the absence of 5W-30 in terms of meeting the VW tolerance standards bulletin. 

It would be foolhardy for VW or any car manufacturer to restrict car owners to a particular brand of engine oil, even when they recommend one by inscribing its name on the oil cap due to research and development cooperation agreements.

It is critical to find an engine oil brand that meets the recommended standards above.


Hello Paul, what is car screen wash made of and can I make my own to save money?


Hello Mercy, windscreen wash fluids are designed to wash car windscreens and the wind screen wiper as you drive. These fluids come in specified containers where they are delivered by jet spray powered by electric pumps to clean your windscreen, prevent streaking which blurs your view and damages wipers, keep the pump and jets lubricated and free of corrosion damage while preventing growth of infectious bugs in the windscreen washer fluid reservoir. In countries that experience winter, these fluids help to de-ice windscreens.  Most windscreen wash fluids are made of methanol and alcohols such as ethylene glycol. They are blended carefully to prevent causing damage to the windscreen glass, rubber wipers and metal materials they are meant to clean and protect.

The process of composing and blending windscreen washer fluids involves deliberate use of specific amounts of chemicals such as 20 percent ethanol, five percent anionic surfactants and less than five percent anionic surfactants. In order to make your own windscreen washer fluid, you need to have some background knowledge of the chemistry involved and specific amounts of chemicals needed to compose the right fluids in order to achieve the above mentioned performance and protection standards.

That is why it is better to use the windscreen fluids already made for you. There are several home made recommendations for windscreen wash fluids which one can try, at their own discretion (and risk of causing damage), in the absence of the manufactured fluids. Some people use a blend of white vinegar, rubbing alcohol, glass cleaner, small detergent and water. The challenge of using plain water and detergent (soap) is that it tends to be corrosive and causes corrosion (rust) damage to the washer pumps and jets.

The wiper rubber lifespan is reduced by streaking while tough tree sap and road soot may not be effectively cleaned. A silent danger is growth of infectious bugs in the washer reservoir, which can cause infection to you.

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