If you do decide to give your garage the oil to perform the change with, there are some things to look out for. On the face of it, it seems perfectly logical that you’ll save some money by supplying motor oil yourself. Whether it’s enough to make the aggravation worthwhile is another question.

How much engine oil does a car need?

That depends on how big the engine is. The size of the engine is measured in CC (cubic capacity), or the greater metric denomination which is litres. So a 1,000cc engine is 1.0-litre. The bigger the engine, the more oil it will need.

Most cars have four-cylinder engines that are somewhere between 1,000 and 2,000cc (1.0 and 2.0-litres). These will need between 3.5 and 5 litres of engine oil.

The easiest way to find out how much oil a car needs for an oil change is to look in the user manual. But the majority of regular cars in the UK will need around 5 litres of oil when their oil is changed.

If you want a rough guide to how much oil your car will take, this website has a handy tool.

What oil does your car need?

When your car has an oil change, it’s important to get the right oil for your model. We explain here why different cars need different types of oil. But you can find out which oil your car needs by again, looking in the user manual.

Will supplying your own oil save you money?

Go and buy the right engine oil from a motor retailer or online and it will doubtless save you some money. How much is debatable.

We looked at oil for a Mazda MX-5 series 3. Our garage charges £46.25 for five litres of the recommended 5w30 oil. We then went online to Mx5parts.co.uk and it would charge us £47.95. At Eurocarparts, you can get the same oil for £41.99 so it’s definitely worth shopping around.

Even so, there’s very little difference between these and what the garage charges. The Mazda engine is derived from a Ford. As it’s probably a popular oil, the garage likely buys its oil in bulk at a trader’s discount. When its margin is added on, it brings it up to retail price. In addition, the oil we were buying was, in both the above examples, a quality Mobil product.

Is it worth buying cheap oil?

That’s an entirely different question. Oil is a vital component when it comes to performance and reliability. You want a quality product that you know is going to last for its lifetime in the engine. Buy a poor-quality oil and your engine could suffer internal damage.

That said, if you don’t care about the quality of your oil, you can save a sensible amount by supplying your own. But don’t expect the garage to be overly pleased. And it will doubtless say it can’t give any warranty over the work if you supply the oil.

We found five litres of 5w30 from a brand we’d never heard of being sold on eBay for £20. Less than half the price then. But there’s no guarantee that it’ll be any good…