Why Your Turbo Blows Oil

Oftentimes if the turbo in your vehicle begins blowing oil, people will tell you that the turbo seals must be bad but this is usually an unfounded claim. A lot of the time your turbo can still be in perfect working condition but blowing oil, so with that in mind here are a few of the most common problems and reasons that your turbo is blowing oil.

• The Oil Drain Is Too Small– If you purchase an aftermarket drain, oftentimes the fitting has too small of an inside diameter. This is the most common cause of oil coming from the turbo because a factory MHI Drain has 16mm inside diameter while most aftermarket drain fittings have an inside diameter of 12mm. This size difference then causes the oil to not drain efficiently and the oil can back up inside the cartridge. Coupled with new oil filling up the cartridge and all of the old oil not being removed, the oil pressure will build up and then be forced out through the seals.
• Blocking The Crank Case Ventilation– If the crank case ventilation gets blocked, the pressure inside of the oil pan will then build up. Because the crank case is pressurized, this no longer allows the oil drain from the turbo at a proper rate and will lead to the turbo blowing out the excess oil as a result.
• Higher Oil Levels– Sometimes the amount of oil in the oil pan can be higher than the oil seals. If there is too much oil in the pan or if the turbocharger in your car is relatively lower, then oil can get through the seals and begin to blow out.
• Oil Pressure Too Low– If the oil pressure is too low, it can cause the internal parts of the turbo to wear out such as the seals. This occurrence can lead to the turbo needing to be rebuilt but is usually extremely rare. On the flip side, the oil pressure being too high will never be a problem unless your oil drain is not big enough. An oil drain that is too small can lead to blockages as it simply cannot handle the volume of oil going into the turbo and you can see oil begin to blow out of the turbo.
• Oil Restrictor In A Journal Bearing Turbo– If you have an oil restrictor in a journal bearing turbo, it can sometimes cause a turbo to blow oil. This happens because the restrictor will starve the turbo of oil, which will cause all of the internals of the turbo (including all of the seals) to wear out. Avoid using an oil restrictor with a journal bearing turbo and if you think the oil pressure is too high, then get a drain with a larger diameter to better regulate the flow of oil.
• Shutting The Car Off Still Hot– After driving your car, don’t turn it off immediately after coming to a stop. Instead, let the engine idle for a few minutes first to allow the oil to circulate through the turbocharger. This removes the heat from the internal parts of the turbo and if you do not allow the engine to idle before turning it of, then the next time you start your car the internals of the turbo can be dry. This can cause accelerated wear and tear on the internal components of your turbocharger.
• Improper Oil Weight– Similar to the engine, a turbocharger has a particular type of oil that needs to be used for maximum performance. If the oil you use is too thin for the temperatures of the turbo, then it can result in the turbo blowing the oil out. Make sure you know the type of oil best suited for your vehicle or take it to an auto mechanic that you can trust.
• Contaminants In The Oil– The least likely cause is also the most severe because any contamination in the oil can quickly destroy your turbocharger. Whether it is debris from a blown engine, sand blast media, or anything that fell into the oil pan, it can have disastrous effects on the vehicle. This is a worst-case scenario because it will often require the engine to be rebuilt and flushed and should debris get trapped in the oil journal, it will never leave/be cleaned regardless of how much you change the oil.

Final words

Owning a vehicle with a turbocharger is a great way to get higher performance and power from your driving experience but understanding the maintenance requirements will ensure it stays in good working condition. While others may tell you that oil blowing from the turbo means the seals are bad and need to be replaced, knowing the likely causes will help you save time and money.

Jordan Weine
Owner – Bay Diagnostic
Serving Brooklyn Since 1985

For over 37 years Bay Diagnostic has been a Brooklyn staple helping you get back on the road faster than the dealer can. A full-service automotive repair shop in Brooklyn that specializes in scheduled service, preventive maintenance and concierge service. At Bay Diagnostic, you will come to expect what the automotive repair experience should be, fast, easy and reliable. A one stop shop for your vehicle needs.

We proudly service Audi, BMW, Land Rover, Mercedes, Mini, Porsche, Smart Car and Volkswagen vehicles.