The oil coming out of the turbo will have lots of air in it. From the shaft speed of the turbo interacting with the journal bearings or ceramic ball bearings.
That air mixed with the drain oil has lots of air bubbles in it. That is why the drain needs to be much larger vs the inlet oil feed side of the turbo. If you dump the drain oil in the timing cover you are guaranteed to be above the oil level in the pan. That is what you want.
You DO NOT want to put the oil drain below the oil level, EVER!!!!!!
The pressure will build up in the line and the CHRA and you WILL push oil past the Turbine oil ring seal and into the exhaust.
If you do that, hire your vehicle out to kill Mosquitoes.
We have run convential oil in turbos for many years in small sales volumes. When we got into the 2 Million Volume level now we had people driving the cars/truck winter or summer in hot and very cold conditions. So the oils today are more like 5W 30 synthetic blends. Mostly this is for cold starts to get the engines running quickly and stop/start engine strategies.
Typical turbos have water cooling built into the CHRA housing so they could live for many years without synthetic blends. We put the synthetic blends in the engines not for the turbos that ALREADY have cooling provisions) but for F.E. and 5000 mile oil changes.
Tom V.
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"Engineers do stuff for reasons" Tom Vaught
Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
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