Buy 10W-40 engine oil

10W-40 is the oil for engines built before the long-life era and for vehicles with high mileage: a thicker oil film at operating temperature than a 5W-30, and therefore less oil consumption in engines with wider bearing clearances. Check the approval in your owner's manual before buying - or select your vehicle in the oil finder.

Which vehicles 10W-40 is intended for

The 10 before the W means the oil is more sluggish in frost than a 5W-30 or 0W-30, but it copes with a northern European winter without trouble. The 40 after it is the actual reason for this grade - at 100 °C a distinctly thicker oil film stays in place.

That suits:

  • cars and vans up to roughly the year 2000, without long-life servicing
  • engines with high mileage that measurably use oil: the thicker film seals wider clearances better
  • commercial vehicles and agricultural machinery, where a multigrade of this class is the standard
  • motorcycles with a wet clutch, provided a JASO MA2 approval is in place

It is not suitable for modern engines with a long-life interval, narrow oil galleries and a particulate filter: 10W-40 is too thick there, and most oils in this class are not Low SAPS. If you need a long-life approval, 5W-30 is where to look.

Semi-synthetic or fully synthetic

10W-40 comes in both builds, and that is the biggest price difference within the grade. Semi-synthetic oils are the normal case for older engines with no particular approval. Fully synthetic 10W-40 oils resist ageing and shear better - worth it for long standing periods, towing, or engines that run hot in summer.

Price per litre is a legitimate selection criterion here, as long as the required approval is met: on an engine with no OEM specification, the matching ACEA class is enough.

Common approvals for 10W-40

  • ACEA A3/B4 - the classic high-performance class with no ash limit, the normal case for 10W-40
  • VW 501 01 / 505 00 - older VW, Audi, Skoda and Seat engines
  • MB-Approval 229.1 and 229.3 - older Mercedes-Benz engines
  • API SL to SN - imported and US vehicles
  • JASO MA2 - motorcycles with a wet clutch

If your owner's manual names an approval that is missing here, the oil finder gets you to the answer via the vehicle.

Pack sizes: from the bottle to the drum

For a car oil change the 5 litre container is the usual size; with several vehicles, the 20 litre can. Workshops, fleets and farms typically take 10W-40 in a 60 or 208 litre drum - it is the grade with the highest turnover by volume, because it covers a broad, older vehicle parc. Larger quantities and special items on request.

At high mileage the oil level is a more important number than the interval. An engine that noticeably needs oil wants checking every 1000 to 1500 kilometres - and with a 1 litre bottle of the same product in the boot, not with whatever the filling station happens to have on the shelf.

Frequently asked questions

Can I run 5W-30 instead of 10W-40?

Only if your manufacturer approves it. 5W-30 is thinner at operating temperature; in an older engine with wider bearing clearances that can increase oil consumption. The reverse applies too: a vehicle that calls for 5W-30 should not be given 10W-40.

Is 10W-40 suitable for diesel engines?

Yes, provided the approval fits - ACEA A3/B4 covers petrol and diesel alike. It is only the wrong grade for diesels with a particulate filter: those need a Low SAPS oil, that is an ACEA C approval such as ACEA C3.

How often does 10W-40 need changing?

As the manufacturer specifies, usually once a year or at a fixed mileage limit. Long-life intervals do not apply to this grade - they require a fully synthetic oil approved for them. Change earlier if you do a lot of short journeys.

Can I mix semi-synthetic and fully synthetic 10W-40?

Short term yes: both are formulated to the same grade, so topping up is uncritical. Long term you are better off with one product, otherwise the properties average out towards the weaker oil - and never mix across different approvals.

Is 10W-40 also suitable for motorcycles?

Only with a JASO MA2 approval. Car oils contain friction modifiers that make a wet clutch slip. Look for JASO MA2 on the container, not just at the viscosity.