Buy 0W-40 engine oil

0W-40 joins both ends together: the cold-start behaviour of a 0W oil and the load-carrying film of a 40 grade at operating temperature. That makes it the grade for powerful petrol engines, performance engines and vehicles driven hard all year round. Check the approval in the oil finder.

What makes 0W-40 special

An oil that still flows at -30 °C and carries load like a 40 grade at 100 °C needs a high-grade synthetic base oil and a shear-stable viscosity package. That is precisely why 0W-40 usually sits at the upper end of the price range - and why it makes sense where both ends are needed.

Typical vehicles:

  • powerful naturally aspirated and turbocharged petrol engines, often with a Porsche, AMG or M badge
  • vehicles with a high full-load share: motorway, towing, mountain passes, the occasional track day
  • older high-performance engines for which the manufacturer requires MB 229.5 or ACEA A3/B4
  • vehicles that start cold in winter and run hot in summer, with no oil change in between

Approvals typically printed on it

  • MB-Approval 229.5 - Mercedes-Benz without particulate filter, high reserves
  • Porsche A40 - approved for most Porsche petrol engines
  • BMW Longlife-01 - BMW without particulate filter, including many M engines
  • VW 502 00 / 505 00 - VW Group petrol engines and older diesels
  • ACEA A3/B4 - the classic high-performance class with no ash limit

That last point is also the limit: most 0W-40 oils are **not** Low SAPS. They belong in a vehicle with a diesel or petrol particulate filter only if a C approval or a corresponding manufacturer approval is expressly printed on the container - otherwise the way through is 5W-30 or a C3-capable 5W-40.

0W-40 against 5W-40 and 0W-30

Against 5W-40: identical behaviour in a warm engine, a better cold start, a higher price. Against 0W-30: the same cold start, a thicker oil film in the heat - at the cost of slightly more internal friction and, as a rule, no long-life approval.

As always, what decides is not the ranking of these properties but what the manufacturer has approved. A 0W-40 is not a "better" oil for an engine designed around a thin long-life oil.

If you take the car on track occasionally, keep an eye on the oil temperature and change by that rather than by mileage: a single track session stresses the oil more than a thousand kilometres of country road.

Frequently asked questions

Is 0W-40 better than 5W-40?

At the cold start yes, in a warm engine no - there both carry the same load. The extra cost pays off with cold winters, frequent cold starts and vehicles parked outdoors. The precondition remains that your manufacturer approves the grade.

May 0W-40 go into a vehicle with a particulate filter?

Only with an express Low SAPS approval. Most 0W-40 oils are ACEA A3/B4 and therefore not low ash; they clog the filter. Check the container for a C class or the matching manufacturer approval.

Is 0W-40 suitable for track use?

For occasional track days a high-grade 0W-40 with MB 229.5 or Porsche A40 is a common choice, because the oil film stays stable at high oil temperature. For regular racing your engine builder or team gives a specification of its own - and then that is what counts, not the grade.

Can I mix 0W-40 with 5W-40?

For topping up on the road yes, provided the approval is the same. Long term you are better off with one product: at the cold start the mixture behaves like the poorer of the two oils, and you are paying for properties you then do not have.