Oils, lubes & additives 40 www.aftermarketonline.net SEPTEMBER 2025 Lifeblood of turbochargers Tom Wright, group product manager at Melett, outlines the core purpose of oil in relation to the turbocharger Lubrication is a key element to ensuring a turbocharger is doing its job correctly. When fitting a replacement turbo, the oil system must be primed and in full working order. Dirty oil, often referred to as ‘oil contamination’, is one of the top killers of a turbocharger. When repairing the vehicle, if the oil system is not emptied, purged and changed correctly, it can leave debris from the previous failure. If a damaged, or poor-quality oil filter is used, this is another way debris can pass through filters into the oil system. Liquid contaminants can also lead to premature oil degradation and increased corrosion and wear. Technicians should also check for engine wear, that could leave swarf deposits, and replace or clean oil inlet pipes and in-line micro filters. Vehicles should be serviced annually or every 10,000 miles, as well as changing the oil in accordance with the vehicle manual. Insufficient lubrication, also known as oil starvation or lack of lubrication, is often caused by blockages in the oil feed pipe and micro filters within, damaged or bent oil feed pipes, a lack of priming of the new turbo, as well as a damaged or worn oil pump, or sludge and coke build up in the bearing housing from hot shutdowns. Ensuring correct oil flow is a must. Priming the turbocharger and oil systems can stop the turbo from instant failure. Vehicle owners should also be aware of the importance of allowing time for the engine to warm up at the start of each journey and cool down at the end. Oil leaks are somewhat of a myth when it comes to the turbo being at fault. The biggest cause comes from the environment in which the turbo is situated. There are very few cases where an oil leak happens because of a component or manufacturing issue. Leaks can occur when an engine is running on idle, because the pressure within the housings is lower, which in turn can lead to a vacuum that causes the oil to leak into the turbine housing. Once the engine starts to run at normal speeds the pressures will be restored, and the leak will stop. Other things to consider include ‘engine blow by’ and ‘crank case blow by,’ both of which cause the same effect, as they increase the pressure in the crank case. Oil leaks can also occur on VSR (high speed) balancing machines, as the ambient pressures required to create the seal are not present as no housings are used. When it comes to leaks, it is imperative that the vehicle technician ensures air, exhaust, and oil drain systems are clear from blockages or restrictions, before moving on to check there are no leaks in the exhaust system. The use of silicone on oil gaskets is not advised as both can easily become detached and block oil passages. Similarly, technicians should ensure DPF and catalytic converter are free of blockages. Always use correct gaskets and O-rings and the correct standard of turbine and compressor housings. Finally, technicians should check for correct oil levels and pressure.
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