A tidbit I'd like to share is when I first put an oil pressure gauge on the car I thought it was broken because at idle it had 90-100 psi of oil pressure. When I revved it it might go up 5 psi but basically stayed around 100 psi. Honest to say I was quite relieved once the oil warmed up it was only 25-30psi idle, but a quick rev to 1500 rpm and the oil was right back there at 100psi and would stay till redline at 7000rpm. It turns out that my car has a oil pressure regulator bypass in the block and these motors must have quite a bit of bypass at high rpm even considering they make full pressure at 1500 rpm when the enigne is hot. Under normal operating conditions I can't tell which oil I had in my car from the oil pressure.
I might try that rotella T6. The reason I stayed away from diesel oils in the past is because I run the stock catalyst and want not to damage it with a oil loaded up with additive that reacts badly with the platinum in the catalyst. It looks like it is rated SM which mean its safe for catalysts.
First, welcome to BITOG.
A couple of comments on your oil pressure readings that might help.
OP does not correlate well with the KV100 spec' of an oil but rather the more accurate HTHS viscosity spec'.
Secondly, you really do need an oil temp' gauge, particularly in a turbo engine, to eliminate the temperature variable and therefore be able to compare the actual operational viscosities of different oils. A temp gauge will also make it possible to see whether the oil you're running is shearing with use.
Regarding oil choice, you may want to try Red Line at some point, specifically their 5W-30 grade. I know it's a bit more expensive but this POE/PAO based, VII free oil is ideal in high stress turbo applications. It's impervious to shear, and with it's HTHS vis of 3.8cP is more a kin to a 40wt oil. For example you'll get higher OP with this oil than even the heavy GC.
Thank you for the welcome.
I use oil pressure gauge to get an idea of the temperature of my oil during hard drives. The cruising oil pressure remains constant due to the in-block regulator bypass but the idle OP will vary. I agree it would be easier to compare oils and check for shearing with an oil temperature gauge. (I opted for a oil pressure, exhaust temperature, and boost instead of oil temperature). Thats an interesting bit of info about OP having more correlation with the HTHS then the KV100.
Also I don't think redline oil is API certified, it may meet API certification but isn't officially certified. Regardless of the quality of the oil I will stay with certified oils as recommended by my owners manual to stay within warranty requirements. I don't have any idea why its not certified other then they are a small specialized manufacturer.
