What Oil to Use for My Car?

Checking your engine’s oil should really be as routine as checking your tyre pressures and tread depths. Except, of course, none of us does either of those basic checks very much either. Which is silly — the tyre checks can save your life, and regular oil checks and changes can save the life of your engine. You might find yourself asking, what oil to use for my car? Read on as we discuss.

It’s no exaggeration to say that the best way to keep a car’s engine running reliably for years is to check and change the oil with great regularity. That and regular, gentle driving are the best solutions to lengthy engine life.

What’s the best oil for your car?

But, there’s a dilemma. What’s the best oil for your car? And how do you choose from what is, frankly, a bewildering choice of brands and product codes. Well, here’s how you can cut through the noise a little…

The first thing is to check your car’s handbook. Again, that’s something that too few of us do very much, but alongside all sorts of other handy information, there will be a listing of the minimum standards for oil that should be used in the engine, and probably a recommended brand and type of oil. Obviously, such recommendations are not hard-and-fast rules, but they can be worth following, especially when it comes to high performance engines which may have been specifically designed around one particular type and brand of oil.

It helps if you can decode the numbers marked on each container of oil. These are usually two groups of letters and number — 5W-30 or 0W-40 for example. Those refer to the viscosity of the oil — which is basically a description of how runny the oil is. If you think of flowing water, that has very low viscosity, while honey would have very high viscosity. The numbers on the oil refer to the oil’s preferred viscosity in winter and summer. The ‘W’ number means that the oil can remain properly viscous down to a low temperature, while the number after the dash refers to the oil maintaining that viscosity in higher temperatures.

Incidentally, the numbers don’t refer to a specific temperature. They’re actually just numbers agreed upon by the Society of Automotive Engineers (SAE) that indicate a performance range — a 0W-30 oil doesn’t stop working at 0-degrees, or 30-degrees for example, it just means that it’s fine to use in very low temperatures, up to medium-to-high temperatures. A 10W-40 oil should be fine in pretty much any conditions that Ireland’s climate can throw at it.

Once you’ve worked that bit out, and looked up the minimum requirements for your car, it’s time to think about oil specifications. These are set out, for Europe, by the ACEA, the umbrella organisation that represents Europe’s car makers, and they are the minimum standards for oil for use in modern car engines.

The ACEA’s standards include:


  •   A1 Fuel economy petrol
  •   A2 Standard performance level
  •   A3 High performance and/or extended drain
  •   A5 Fuel economy petrol with extended drain capability


  •   B1 Fuel economy diesel
  •   B2 Standard performance level
  •   B3 High performance and/or extended drain
  •   B4 For direct injection passenger car diesel engines
  •   B5 Fuel economy diesel with extended drain capability
  •   E1 Non-turbo charged light duty diesel
  •   E2 Standard performance level
  •   E3 High performance and extended drain
  •   E5 High performance and extended drain including some API specs
  •   E6 Euro I to VI engines –with EGR, with or without DPF and engines with SCR NOx reduction
  •   E7 Euro I to V engines – most EGR  and most SCR NOx engines but without DPF
  •   E9 Euro I to VI – with or without DPF, most EGR and most with SCR NOx reduction

On top of that, if you have a diesel-engined car with a particulate filter, you’ll need to use what’s called a low SAPS oil — one with a low sulphur content. SAPS stands for Sulphated Ash, Phosphorous, Sulphur, and if you use normal oil in such an engine, you can end up clogging up your particulate filter which is expensive to fix or replace.

Thankfully, there are some helpful online tools to guide you through this morass of oil choices. German oil and lubricants maker Liqui Moly has a particularly useful one, and so does motor factors chain Halfords. Basically, as with most car components and products, you will get what you pay for when it comes to oils. Oil is utterly critical to the healthy functioning of your engine, so as with tyres and brakes, it’s not worth skimping on — you’ll end up paying bigger bills later on.