Engine oils

The following is intended to provide a better picture of the motor oil market in general. To be more concrete, the example has been worked out with a specific oil standard and some brands of lubricants. Suppliers have been asked to respond to the points below.


Citing engine oil specification “fiat 9.55535-DS1”: The only approved engine oil is Selenia WR Forward 0w30. However, there are many types of motor oil that claim to meet the specification. So the emphasis is on “meet” and “approved”.

This creates a “FUD” (Fear, Uncertainty and Doubt) situation for the consumer who, on the one hand, likes to look for a good price-performance ratio and, on the other, realises that motor oil must be of good quality to avoid engine wear – or worse, engine damage.

Moreover, many garages will use an oil where maximisation of both profit and quality is important. In that case, consumers will have to trust the garage company and will usually be kept in the dark about the quality of the motor oil used, which most consumers are also not interested in.

This article arose from a question on the FiatForum. The thread can be found here…

A quote from Royal Dutch Touring Club ANWB (comparable to AA and ADAC) as a response to this post:

The price differences between different oil brands is indeed sometimes excessive. As far as we are concerned, there is no reason to specifically advise against a cheaper brand, and a three times more expensive brand is certainly not three times better for that reason. It should also be clear that oil prices at garages are so high that they have a substantial profit margin on them. There is a very clear business model behind this.

We don’t know of any test where possible differences in quality are shown very concretely. Perhaps also because there is no reason to worry about the quality of cheap brands. And it is often a certain marketing strategy to tempt consumers to choose a more expensive product, because by definition this is always better. But a cheaper product is often more than good enough.

Example products

The following example table lists some oil types meeting “fiat 9.55535-DS1”. This illustrates the difference in pricing.

SELENIAWR Forward70253EF8EU5L178.00
SHELLHelix Ultra ECT C2/C35500463065L95.00
  • Prices are competitive street prices in The Netherlands, 2023.

Some questions

The relevant manufacturers have been asked to answer the following questions:

  • Do you believe that, concerning specifications, “meet” versus “approved” is tying the make and type of vehicle to the make and type of motor oil?
  • Do you believe that the price of motor oil almost always reflects its quality?
  • Do you consider that the price of motor oil has a strong relationship with brand awareness?

The specification fiat 9.55535-DS1 is not public but known to you. On that basis, you are asked to answer the following statement with “agree” and “disagree”.

  • As a general rule, you can say that any motor oil that claims to meet specification “fiat 9.55535-DS1” is safe to use for the relevant vehicles.

Of course, there are quality differences between different brands and types of oil. Could you estimate a percentual longer or shorter car engine life under normal use and proper car management, using your oil as specified, compared to the only approved oil?

Finally, do you wish to make additions to this article?

So far, Selenia, Shell and Pemco did not reply.


In tribology, the viscosity of an oil determines how well an oil performs its lubricating function. Viscosity can be described as cohesiveness or fluidity. In an engine that starts up ice-cold and can also get more than boiling hot, that oil will always have to be thin enough to be pumpable and thick enough to lubricate. That is a challenge!

Viscosity can be expressed in numbers. One test for this is how fast an oil runs through a tube. You can compare that to an hourglass with oil instead of sand. Cubic millimetres per millimetre of height per second go through the tube and then you immediately have the unit of viscosity:

\frac {\frac {mm^3}{mm}}{s} \Rightarrow {\frac {mm^2}{s} \Rightarrow mm^2/s

By standardising the test method (DIN, ISO, ASTM), you can compare the viscosities of various oil brands and types.
KV40 and KV100 are the viscosities at 40 and 100 degrees Celsius, respectively.

Another important number is the viscosity index VI. The higher that number is, the more resistant the oil is to lowering viscosity as temperatures rise. Put another way, a high VI indicates that the oil does not become too thick when the oil gets colder. Thus, a high VI ensures a more consistent viscosity.

Finally, it is important to realise that engine manufacturers specify for each engine type the limits within which the numbers KV40, KV100, VI (and other parameters) should lie. Manufacturers test their own oil and then state that an oil meets a certain specification of a car brand. In practice, you can assume that this is correct.

Based on public data, here is a table with properties of some “fiat 9.55535-DS1” oils:

VI Viscosity Index ISO 2909 / ASTM D2270
KV100 Kinematic Viscosity @100 °C (mm2/s) DIN 51562-1 / ASTM D445
KV40 Kinematic Viscosity @40 °C (mm2/s) DIN 51562-1 / ASTM D445
FP Flash point (°C) ASTM D92
PP Pour point (°C) ASTM D97

Default sort order: Viscosity Index

ShellHelix Ultra ECT C2/C3 0W-3020411.958.7226-51
PetronasSelenia WR Forward 0W-301949.45?216-50
RAVENOLFES SAE 0W-301869.447.3236-57
CastrolMagnatec 0W-30 GS1/DS117811.1161202-45
ValvolineSynpower DT C2 0W301929.446226-51
QuartzIneo First 0W-301879.950.34230-42
Motul8100 Eco-clean 0W-301819.851.2222-45
Liqui MolyTop Tec 4310 0W301759.550?-39
Pronex0W30 C2 BHDI1729.652230-48
FuchsTitan GT1 Pro 2312 0W301659.553.5?-45
Millers OilsXF Premium C2 0w30?9.9?>200?

My choice

I concur with the view that a cheaper product is often more than enough. Still, there are clear differences visible between the products. From my point of view, the use is mainly long distances and somewhat higher use temperatures. If you look at the viscosity index column, you will see Helix at the top with a viscosity at 100 °C that is also the highest. Taking into account that there are excellent offers and that the oil is readily available internationally, this was ultimately the reason for choosing this.

I paid €8.66 per litre, delivery included. Those who take the trouble to search the internet will be rewarded with competitive prices. This site is not sponsored in any way, I pay everything myself. I do want to mention that the oil was bought from https://www.misteroil.eu/ , 3 times 5 litres, so it will last me a long time – synthetic oil has a shelf life of many years.

Those who drive short trips or live in a cold climate, for example, may want to choose a different oil. And as mentioned, the cheapest will certainly not be a bad choice either. It was an extraordinary quest to finally come to a choice and I hope this article gives some insights.

My oil was delivered to a collection point. This was, how ironic, a Shell petrol station. As I walk out with my box of oil, I see in the corner of my eye exactly the same oil listed for a price of €24.50 per litre. That’s three times what I paid for it! There is a curious pricing mechanism behind it. You could almost say it is a somewhat shady trade.

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