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How about 10W30?
I am not an oil scientist but if 5w20/30 is good enough for turbo bearings.. how would it not be good enough for water pump bearings?
One is tens of thousand rpm, the other is below 6000 rpm .
We should be seeing mass failures of turbocharged vehicles running on ILSAC 5w30.
But we are not.
I run 5W50 in my 2014 but it is a Track Pack which calls for 5W50. Internally the engine is the same as a GT, but it has an oil cooler, larger radiator, and overheat protection turned off in the PCM.
The turbo spins at around 300K rpm when you're giving it boost at around 2000 engine RPM. No ILSAC oil should be run in any of these engines because the Turbo cooks the oil, and most of these crappy ILSAC oils are Group III petroleum or GTL based. If you want your turbos and your engine to last as a whole, then you need a good PAO/Ester (most high-end oils like Red Line Oil or AMSOIL are a blend) to withstand the heat while holding on to the additives and resisting fuel dilution. Or you can run Castrol EDGE 0W-40 which is PAO+Group III and is cheaper than most high-end ILSAC oils, but it won't be as good as AMSOIL or Red Line Oil.
if by 300k you mean 100-120k you would be correct
With a large viscosity spread like a 5W-50, oil companies use a lot of VI's to get that range. For a number of years I had a 2012 Boss 302 Mustang and it specified 5W-50. Found a person on another site who had developed quite a database of how resistant or not a large number of oils were to shearing in both the coyote v8 and the older modular v8's. Interestingly, his data, derived by a LOT of oil analysis, showed that any 5W-50 will shear down to an effective 30 weight in around 1000 miles. As I recall, he checked the Motorcraft variant of that viscosity, as well as the Mobil 1 and, Amsoil. All had sheared to an effective 30 weight in around 1000 miles.
It was his contention that Amsoil's SS 10W30 was essentially straight PAO 30 weight which due to it's cold flow ability, also met the requirements of a 10W-30.
And for a personal data point, I had an oil pressure gauge on the Boss, and with 5W50, cold (even 60 degree ambient) starts resulted in initial oil pressure of 110 psi, which lowered to the mid 30's when fully warm at idle. When I began using the Amsoil SS 10W-30, cold start oil pressure still spiked to almost 90 psi, and settled down to the same warm idle pressure as the 5W-50 of mid 30's.
If you going to go thick, use a VW 502 type 5W30 that has a HTHS of 3.5+.
If you going to go thick, use a VW 502 type 5W30 that has a HTHS of 3.5+.
Though that might be true, Motorcraft produces excellent UOAs in my GT350R. I've not found a reason to switch to other oils that meet (or claim to exceed) the spec e.g. Lucas and Amsoil.Most of the time reports Ive seen show the motorcraft 5w-50 sheers down to a 40 weight pretty quickly anyways.