5 litre bottle of fully synthetic 5W-30 car engine oil

What Engine Oil Does My Car Need? A Simple UK Guide

Choosing engine oil comes down to two things: the viscosity grade (for example 5W-30) and the specification or approval your car's manufacturer asks for (for example ACEA C3 or VW 504 00). Get both right and any reputable brand will protect your engine. This guide shows you where to find them and how to match them to an oil.

Quick answer

  1. Find the oil requirement in your owner's handbook or service book. It lists a viscosity grade and one or more specifications or approvals.
  2. Check the oil filler cap or the label under the bonnet. Some manufacturers print the grade there.
  3. Choose an oil that shows both the same viscosity grade and the same approval on its label or product page.
  4. No handbook? Use our oil finder, or send us your registration and we will check it for you.

Step 1: find your viscosity grade

The viscosity grade looks like 0W-20, 5W-30 or 10W-40. The number with the W (for winter) shows how easily the oil flows when the engine is cold. The second number shows how thick the oil is at normal running temperature. Many modern engines need thin oils such as 0W-20 or 0W-30, while older engines often use 10W-40 or 15W-40. Our guide to engine oil viscosity grades explains the numbers in detail.

Step 2: find the specification or approval

Viscosity alone is not enough, because two 5W-30 oils can be built very differently. Your handbook will name one or more standards the oil must meet:

If your handbook names a manufacturer approval, choose an oil that carries it. A manufacturer approval adds the car maker's own engine tests on top of the general ACEA category it is based on.

Step 3: match it to an oil

Every product page on Nitroma Lubricants has a Specifications at a glance table listing the viscosity grade, industry specifications and manufacturer approvals. You can also browse by:

Common mistakes to avoid

  • Buying by viscosity only. A 5W-30 without the approval your engine needs may not give the protection the engine was designed for.
  • Using a full-SAPS oil in a car with a diesel particulate filter (DPF). Most modern diesels need a low or mid-SAPS "C" category oil, such as ACEA C3, to protect the filter.
  • Using an oil made for newer engines in an older one. Some low-viscosity approvals, such as VW 508 00 / 509 00 (0W-20), are not backwards compatible. Only use them where your handbook lists them.
  • Overfilling. Fill to the level shown on the dipstick or dashboard, never above the maximum mark.

How much oil will I need?

Most family cars take between 4 and 6 litres for an oil and filter change, while larger engines and vans can need more. Check the exact capacity in your handbook. A 5 litre pack covers most cars with some left for top-ups, and garages and fleets usually save by buying 20 litre packs.

Frequently asked questions

Do I have to use the same brand of oil the dealer used?

No. The brand does not matter as long as the oil meets the viscosity grade and approval listed in your handbook. Keep your receipt so you can show the oil you used met the requirement.

Can I mix two different engine oils?

Modern engine oils are compatible with each other, so topping up with a different oil will not harm the engine. For the best protection, top up with an oil that meets the same grade and approval, and use a single oil for a full change.

Is more expensive oil always better?

Not necessarily. An oil that carries the right approval for your engine is the right oil, whatever the price. Premium brands and trade brands such as Triple QX and MPM can carry the same manufacturer approvals.

What if my handbook lists more than one option?

Any oil that meets one of the listed specifications, in a viscosity grade allowed for your engine, is suitable. If the handbook marks one option as preferred, use that one.

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