Originally Posted By: nickolas84
I was referring to flow to the engine given the pressure relief valve. Unfortunately I don't have oil pressure reading in my engine,
Let me cut you off right there. So you have ZERO practical first-hand experience with this subject and you are lecturing those of us that DO on "how things work"?
Why do you think I told you to pull a valve cover on a cold engine and fire it up to observe oil flow? Because that's the easiest way for you to verify that whatever you are theorizing here is patently false. I've done this. On an SBC, SBF, an old 440 Mopar, even some antique boat engines. I've had the valve cover off a Modular when it was fired up too. They ALL had one thing in common: A whole heck of a lot of oil going all over the place within a couple seconds of the engine firing up. About the only one I can recall going onto the relief was an SBC with an HV pump with 20w-50 in it which would hit 60psi, which was the relief on the pump. Give it some gas and it would go above the relief pressure. It was like Niagra falls in the heads; there was a LOT of oil moving.
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but a friends NC MX5 hits the relief at ~3500rpm when
warm, and that is the norm as far as I know.
The norm for that engine perhaps. What grade of oil is in the pan?
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Around here 5W-XX is what Mazda specs for the MX-5; 0W might be quite different.
5w- what? 5w-20, 5w-50? That's a rather hugely vague area for you to leave open. And no, 0w-xx won't be any different, as the difference between a 3.1cP HTHS 0w-30 and 5w-30 is their performance at -30C and -35C and -35 and -40C respectively (CCS and MRV). Step out of the extreme cold temp range and the behaviour between the oils is basically a wash. The advantage of a 0w-40 over a 5w-40 is its cold temperature performance, not its performance on a 30C start.
It sounds like you don't quite have your head wrapped around viscosity either.
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BITOG recently published "Motor Oil University". You can check it
here MOTOR OIL UNIVERSITY. It goes through all of this and the benefits of modern "synthetic" thin oils in great detail.
As others have stated, that's not recent. It is a relatively old series of articles written by a resident poster, who is a plastic surgeon by trade. A very intelligent man but as JAG has noted, these dissertations that he's authored have resulted in many people thinking they know a lot more than they actually do. And getting many of the fundamental concepts completely wrong.