Overfilling the engine oil is terrible; no matter the vehicle, it can cause significant damage to an engine. But can overfilling oil damage the turbo? It is a question that gets a different answer depending on who you ask. This issue is that if a turbo has failed and the engine is found to be overfilled with engine oil, it’s easy to blame the oil issue. There are instances where oil would be the cause of a turbo failure, which will all be explained in the short article.
Can overfilling oil damage the turbo?
If the engine is so far overfilled, the turbo’s oil return pipe is full of oil; it could damage the turbo. But if the engine is that overfilled, the turbo failing would be the least of your worries. You can read more about the damaged caused by overfilling the engine oil here.
A turbo uses a pressure hose with a restrictor to suck the correct amount of oil into the turbo and then return it to the oil sump when it’s finished. The bore of the oil pipes and the restrictor limit the amount of oil getting into turbo bearings to reduce oil drag. So, overfilling oil would rarely cause a problem unless the internals of the turbo were already weak. Running the vehicle low on engine oil would cause more damage to the turbo than overfilled.
What happens if turbo gets too much oil?
Although you’ve just read that too much oil would not usually damage a turbo, there are instances when too much oil can damage a turbo. But the problems typically start with weak turbo internals instead of the issue initially caused by too much oil in the engine. With too much oil, the pressure in the turbo rises, which puts pressure on the oil seals. The oil seals inside the turbo can leak or force excess oil out of them, and oil will then be found in the intercooler. However, as mentioned, the seals would already be weak or have a little oil to allow extra oil into the turbo.
The other instance you can have a problem with is high oil pressure which can burst oil seals in the turbo. This can result from too much oil being forced into the exhaust system, which results in a build-up of back pressure and increased heat in the turbo. Although turbos are designed to handle relatively high amounts of stress, there is a limit. This high pressure can be started by significantly overfilling the engine oil.
Does engine oil effect the turbo?
Engine oil is used to lubricate the bearings and cool the turbo. Engine oil is passed through very thin oil supply lines to and from the engine via an oil cooler. Sticking to service schedules and replacing the engine oil regularly is very important. It is not just the engine oil level but any minor defect or issue with the oil can affect the turbo in several ways:
- Contaminated oil – Dirty contaminated oil will be drawn into the turbo which could damage the turbos seals, block the oil lines, or damage the bearings.
- Low oil – If the turbo does not get enough oil, the turbo will overheat. This causes unnecessary pressure on the turbo and ultimately the turbo to fail.
- Old oil – Old engine oil has a thicker consistency which will block the oil pipes and not cool or lubricate the turbo as it’s supposed to.
What are the signs of a damaged turbo?
Some of the commonly found signs that indicate a damaged turbo are:
- Loss of performance – The turbos job is to force additional air into the engine, providing that boost of acceleration when hit around 3000RPM. When the turbo has failed or is failing it won’t provide that increase in acceleration.
- Excess smoke from the exhaust – When a turbo fails you can usually see the car produce blue/grey exhaust gasses that are excessive especially when the engine is +3000RPM. This is an indicator some sort of oil seal in the turbo has probably failed.
- Noisy turbo under acceleration – In the centre of the turbo is a propeller and bearing which sucks air in, it can spin at 80,000rpm. If the bearing or the blade becomes faulty, you will hear an unusual loud noise when trying to accelerate
Bottom line
Keeping the engine oil at the correct level will rule out any potential problems associated with over or underfilling the oil. A turbo is one of the last items in an engine bay you should worry about if you drive overfilled with oil. Excess oil fill will rarely damage a turbo; the more common issue is underfilled oil. If you suspect your turbo has or is failing, it would be better to take it to the garage for inspection.
