Now this makes me wonder - What are we measuring when we measure oil
pressure? Why does measured pressure drop with wear? And, possibly most
importantly, given decreasing pressure with wear, is using a
higher-viscosity oil actually a healthy remedy? For instance, you could
imagine using an oil that is extremely viscous (STP?), we could increase
pressure to any number we wanted, but would this oil be so thick that it
never actually gets to the bearing surfaces? I have not even a dim
understanding of this, and it makes me nervous to chase a spec number
without understanding how that spec is really derived (what is its basis in
the reality of the physics and chemistry of the engine environment?) and
what these various remedies do.
Any thoughts?
---
On 10/23/99, Andy Webster wrote:
>Greg
>At the moment I'm using 20w-50 GTX2 just for running in, but once 500 miles
>is up I'm switching to penrite HPR 30 which is 20W-60.
>For worn engines HPR 50(40w-70) is good and HPR40 is in between at 25w-70.
>DOn't mean to sound like an ad but it is good oil. I have seen the
>improvement in pressure that it gives in a worn engine.
>I will also inform you that when my engine blew in August (#2 big end
>bearing disintegrated) it had fairly fresh Mobil 1 in it. That proves
>nothing but it had previously had penrite and been driven harder without
>losing the plot.
>You may have worn bearings along the crank to have such a drop in pressure
>with temperature, as thats where I was at..60 at start, down to 20psi at
>190'& 3000rpm and <10psi at hot idle (Mobil 1).
>Andy
|