Car Engine Oil – The Ultimate Guide

Using the right engine oil and making sure it’s fresh can really make a difference in helping keep your engine running smoothly. Our ultimate guide will break down everything you need to know about engine oil, including how to check and change your engine oil.

Which engine oil for my car?

The vehicle owner’s manual is the most accurate place to find the best information about which exact spec of oil to use in your car. It will provide information on the oil grade required as well as the quantity needed. The oil to use in a car will depend on the engine requirements, each type of oil will have different characteristics to suit a particular scenario.

Types of car oil

There have been several types of car oil over the years:

  • Synthetic oils: These are modern oils created to achieve better performance across applications. They are effectively designed from the ground up, and include additives to aid engine cleaning and stop air bubble formation.
  • Mineral oils: These are classic oils, and are no longer recommended for modern vehicles
  • Semi-synthetic oils: Some applications benefit from having a mix of mineral oils as well as semi-synthetic oil. Coming with less additives, they’re usually a bit cheaper than fully synthetic oils.

What do oil grade numbers mean?

The oil grade is the viscosity grade that’s noted on each bottle of oil, like 15W-40. It refers to the thickness of the oil, and effectively how fast it can flow. The higher the viscosity number the slower it flows. Specifically the first number indicates how quickly the oil would flow at colder engine start up temperatures, the second number shows how the oil flows at normal engine operating temperatures.

Generally, when the oil is less thick it can flow more effectively. Hence, when the number is lower the engine will have better cold start and cold running performance. The number after the “w” describes the viscosity of the oil in more normal temperatures.

Some mechanics may refer to the viscosity as “oil weight” – this is important to understand so you do not get confused when these terms are used interchangeably.

When should you check the engine oil level?

It is best to check the oil when your engine is cold before starting it in the morning, and to do so on a level surface. It will help ensure that most of the engine oil has settled back into the oil sump, enabling a more accurate reading of the oil level.

If the engine has just run it’s important to wait at least 10 minutes before checking to let the engine cool down and give the oil a chance to settle. Further to that, it can help ensure you don’t burn yourself on the hot engine.

How often should you check the engine oil level?

It is recommended you check the oil level every 2 to 4 weeks, to help ensure there’s enough oil at all times to keep the engine running in an optimal way.

Before embarking on a long trip make sure to check the oil level and top up if necessary. Add checking the oil to the list of pre-trip inspections. Many newer vehicles have a sensor that will read out your oil level so you know exactly how much oil you have and if you need to make a trip to the mechanic or to bring out the jacks.

How much is an oil change?

The cost of an engine oil change is usually between £60 and £150, with an average cost of £90. This varies widely depending on factors such as the type of oil used, how much you need, make and model of vehicle, and more.

The type of oil used and the oil quantity needed for your vehicle usually make the biggest impact on the price. Large capacity or performance engines will need better quality oils, in larger quantities.

How to check the engine oil level?

See our full guide to check your engine oil level here (with pictures). Here is a summary of how to check the engine oil level:

  1. Make sure your vehicle is on level ground to get the most accurate reading.
  2. Open the bonnet and locate the oil dipstick.
  3. Remove the dipstick from the funnel, and clean it with a microfiber rag or mechanic’s towel.
  4. Then return the dipstick into the oil reservoir, and remove again to check where the oil level sits between the max and min oil line. If the oil line is above the lower line you have sufficient oil.
  5. Sometimes it is advisable to repeat the process to verify the first reading was accurate.
  6. If the oil level on the dipstick approaches the minimum line, or has dropped below it, make sure to top up the oil. Of course, be careful not to overfill.

ClickMechanic has mechanics who can assist you in changing and checking your oil for you, and giving you appropriate information so you will be more educated in assessing your own oil in the future. Get a price for an engine oil change.

Woman refilling engine oil

How to change your car engine oil?

The oil change procedure will depend on the make and model of your car, but generally the following process will look like this:

  1. Make sure the vehicle is on level surface and securely in place before raising the vehicle.
  2. Protect the surrounding area against spillage.
  3. Remove the oil filler cap and the dipstick.
  4. Drain the oil from the vehicle by undoing the oil drain plug underneath the car, and collect the oil in an appropriate container. Then replace the gasket and refasten the oil drain plug.
  5. Replace the oil filter before adding new oil (an old oil filter would contaminate the fresh oil).
  6. Refill the engine oil via the oil filler cap with the correct oil grade and quantity.
  7. Check the oil level by re-inserting the dipstick (make sure it’s clean prior) and remove to check the oil level is between the min and max lines.
  8. Further top up the engine oil if it is much below the max line.
  9. Refasten the oil filler cap and run the engine for a bit, and once cool re-check the oil level.
  10. Make sure to reset any oil service and quality warning lights, to help signal that the oil change has taken place. In some cases this procedure may require the assistance of professional equipment.
  11. Store the old oil in a sealed container and dispose of it by taking it to an oil bank. Remember, it is illegal to dispose of engine oil by pouring it down the drain or onto the ground.

If you’re not sure how to change the engine oil for your car make sure to get help from a mechanic, who can help carry out the engine oil and oil filter replacement correctly.