10W40 Engine Oil

Is 10W40 the right oil for your engine?

10W40 is primarily suited to older petrol and diesel engines, roughly from the 1990s through the mid-2000s, where the manufacturer specifies this viscosity grade. It works well in high-mileage engines where slightly higher operating viscosity helps maintain oil pressure and may reduce minor mechanical noise. It is not a universal choice: if your manual specifies a thinner grade or a low-SAPS oil for emissions systems, 10W40 is not the right product regardless of engine type.

For short trips and city driving, 10W40 is fine as long as the manufacturer viscosity and specification requirements are met. The driving pattern does not change which oil grade you need; it may affect how often you check the level, since older engines on short runs can consume slightly more oil.

For older petrol and diesel passenger cars and light commercial vehicles where the manual lists 10W40 with ACEA A3/B3 or A3/B4 and API SL/CF, Lindemann Motor Oil 10W-40 SL/CF B4 5L is the straightforward choice.

How to check if this oil matches your manual

Two things must match before you buy: the viscosity grade and the specification codes. Finding the viscosity is straightforward; your manual will state "10W-40" or "SAE 10W-40". The specification codes are the second step, and they matter just as much.

The "10W" tells you how the oil flows in cold conditions: the lower the number, the better the cold-start fluidity. The "40" tells you the film thickness at operating temperature. Both ratings must align with what your engine was designed for.

When the viscosity grade and the spec codes both match what your manual lists, the oil is compatible. Following those manual specs also matters for warranty purposes: if your car is still under manufacturer coverage, check with your dealer before switching products. For a full breakdown of all ACEA and API specification classes, see our Knowledge Centre.

If your manual lists a code not shown here, contact DPP support with your licence plate before ordering.

10W40 vs. 5W40: which do you need?

The number before the W indicates cold-weather fluidity. A 5W40 flows slightly better than a 10W40 at very low temperatures, which matters most during a cold start in winter. At normal operating temperature, both grades deliver the same film thickness: the "40" rating is identical. For most older cars in moderate climates, the practical difference between the two is small.

The more meaningful comparison is 10W40 versus 5W30. A 5W30 is thinner when hot, not just when cold. It is generally intended for modern engines with tighter internal tolerances and fuel-efficiency targets. Using 10W40 in an engine designed for 5W30 can increase internal resistance and fuel consumption, and may not meet the OEM's emission or efficiency requirements.

If your manual specifies 10W40, do not switch to a thinner grade on the assumption it is better.

How much oil do you need, and how often?

Oil change:

• Check your manual for the exact capacity your engine requires.
• A 5L can covers most cars for a full change. Lindemann Motor Oil 10W-40 SL/CF B4 5L is a practical pack size for a full oil change on most older passenger cars.
• Replace the oil filter at every oil change without exception.
• Always follow your manual for the service interval, as it overrides any general guideline.

Topping up:

• Check the level on the dipstick when the engine is cold and the car is on level ground.
• Add oil in small amounts at a time, wait a minute, then recheck.
• Never fill above the maximum mark. Overfilling can cause engine damage.

For a step-by-step oil change guide, see our Knowledge Centre.

What 10W40 does, and what it does not

What 10W40 does:

• Lubricates moving engine parts and reduces metal-to-metal wear.
• Helps carry heat away from hot engine components.
• Keeps combustion residues and soot in suspension until the next oil change.
• Protects metal surfaces from corrosion.
• Maintains oil pressure in engines designed for this viscosity.
• May reduce minor tappet noise in some older engines. This is not guaranteed and it is not a repair.

What 10W40 does not do:

• Does not repair worn piston rings, valve seals, or bearings.
• Does not stop significant oil leaks. For leaking seals, a dedicated oil leak stop product or mechanical repair is needed.
• Does not solve misfires, compression loss, rough running, or sensor faults.
• Does not permanently fix high oil consumption in a worn engine.
• Does not improve fuel economy in engines designed for thinner grades such as 0W20 or 5W30.

After a fresh oil change with the correct grade, you may notice slightly smoother running or a small reduction in mechanical noise in an older engine. Do not expect dramatic or immediate changes; the benefit of correct, regular oil changes is cumulative.

If you need to top up in an emergency and the correct grade is not available, adding a small amount of a different oil grade is preferable to driving with too little oil. Plan a full oil change with the correct single-grade oil as soon as possible afterwards.

Go to a garage instead of just changing the oil if:

• Your oil is milky or grey (possible coolant contamination).
• You find metal particles on the dipstick.
• Your oil warning light comes on while driving.
• Oil consumption is consistently higher than expected for your engine.

These are signs of a mechanical problem that an oil change alone cannot address.

Can you use an engine flush or additive with 10W40?

For a regularly serviced engine in reasonable condition, 10W40 on its own is enough. Additives and complementary products are useful in specific situations, but they are not a standard requirement for every oil change.

• Engine flush: useful before an oil change if the engine has not been serviced in a long time, or if the old oil looks very dark and sludgy. Not required for a regularly maintained engine. (See the Engine Flush category for suitable products.)
• Oil leak stop: for minor seepage at seals, not for significant leaks. Used alongside the correct oil, not instead of it.
• Oil protectors and conditioners: only where explicitly compatible with your engine and oil. Not necessary for a healthy, regularly serviced engine.

These are optional complements for specific situations, not routine additions to every oil change.

If your manual clearly lists 10W40 with ACEA A3/B3 or A3/B4 and API SL/CF, the Lindemann Motor Oil 10W-40 SL/CF B4 5L covers the majority of older petrol and diesel passenger cars and vans in one pack. If you are unsure about the codes in your manual or your car's service history, contact DPP support with your licence plate before ordering.