To be honest it's not only about how thick is the oil. It depends in the weather since the oil heat causes a chemical reaction in the engine oil, which causes the oil's viscosity to change
aleccesarenriquez: From my experience you will have boost creep at high RPM as the exhaust gas flow will not be enough for the wastegate to control the exhaust gas. Unless the manifold worked from inside to force the air to go to wastegate.
If still the turbo manifold is not installed on the...
Don't forget to add check valves for your Feed and return lines. That will prevent and oil leak from the turbos! Also try to install oil feed restrictor 1.5mm for journal bearing turbo.
Good luck with the build!!