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Engines need to be topped up with oil to keep them well-lubricated and safe from damage, wear and corrosion. But what happens if you put too much oil in your vehicle during a lubricant top-up or change? Here are the symptoms of the problem, what you should do if you have used too much oil, and how to find out how much oil your car takes.

The symptoms of too much car oil

Oil pans are specifically designed to hold a certain volume of liquid, accounting for fluid heat expansion and the pressure of the oil on components. If it is overfilled, the following may occur:

  • Dense white smoke – If you drive your car and see plenty of thick, white exhaust smoke, excess oil may be burning within the engine block, although fluids such as antifreeze may also be the culprit.
  • Leaking oil – If there is lots of oil pooling beneath your vehicle, you may have overfilled, but be sure to check if the oil plug underneath the car is loose as that could be the source of the leak.

The effects of too much car oil

If your car receives too much engine oil, your vehicle can be affected in a range of potentially damaging ways:

  • Pressure on crankshaft heads and tails – The head and tail couplers and ends on crankshafts stop oil leaking. If too much oil put in the engine, extra pressure can be put on these components, which can lead to leaks. What’s more, if this occurs on the flywheel end of the shaft, oil can contaminate and damage the clutch.
  • Friction on the crankshaft – When covered in too much oil, the crankshaft and crane can experience greater resistance and friction, causing them to become damaged.
  • Engine wear – If oil is at an incorrect pressure, the lubrication of engine parts will not be properly optimised, causing increased wear.
  • Engine damage – Too much lubricant in the system can cause pressure on the crankshaft to increase. This can result in oil entering the crankshaft exhaust pipe, running through into the combustion chamber, blocking the suction hose with oil soot and potentially leading to engine overload. Overflowing engine oil can also lead to bent engine rods and collapsed valve pipes.
  • Spark plug fouling ­– Excess oil can find its way into spark plugs, which will then need to be replaced.

If you experience any of the above, check your oil level using a dipstick reading. Warm the engine, park on a flat surface, turn off the vehicle, then using a dipstick, read the oil level. This should be between the minimum and maximum markers on the stick.

What should you do if there is too much oil in your car? 

If you have put too much oil in your car, you should drain the excess oil. If you’re not confident doing this, you will need to get your vehicle towed to a mechanic – driving it could damage the engine, requiring expensive repairs. If you want to do it yourself, follow these steps:

  • Read and follow our guide on how to change your oil up to step four.
  • After the excess oil has drained from the engine, rescrew the oil cap, using a wrench if necessary.
  • Check the oil level using the dipstick. If there is still too much, drain more.
  • Refill your oil reservoir to below the maximum level if you have over drained.

How much oil does your car take?

The amount of oil car engines require is roughly between 4 and 8 litres. This differs greatly between vehicles, though generally:

  • Four-cylinder engines need around 4.5 litres of oil.
  • Six-cylinder engines use around 5.5 litres of oil.
  • Eight-cylinder engines require between 4.5 to 7.5 litres.

Always know the exact volume of oil your vehicle needs before topping up or changing. To find out how much motor oil your car requires, check the lubrication section in your vehicle’s owner’s manual. The amount of oil required should be listed in litres next to the type of oil your engine needs.

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