Idle oil pressure

[Alpine 1789]

I drove my SV today for the first time in a couple of weeks and was surprised by the oil pressure at idle. Unless my memory is failing me (always a distinct possibility), my pressure when warm has always been around 25 psi at idle (around 1100 RPMs) and 45 at 3000 RPMs, which I think is pretty close to what it is supposed to be. On a highway drive today it was still 45 when warm but only went down to 35-40 or so at idle.

The only thing that has changed recently is that I switched from Castrol 10W30 to Rotella 15W40. Is the change in viscosity enough to account for the increase in idle oil pressure?

 

[V_Mad]

I would say yes, it is due to the thicker oil. The upper figure has not changed, possibly because that is the release pressure of release valve.

 

[alpine_64]

Jim,

Yes the thicker oil should give you a slightly higher reading, however.. your idle is 1100rpm? That seems high.. I am thinking even worth a warm cam.. 1000 is fine.. and 900 is what i ran mine on even with the DCOES.

 

[Alpine 1789]

Jim,
your idle is 1100rpm? That seems high.. I am thinking even worth a warm cam.. 1000 is fine.. and 900 is what i ran mine on even with the DCOES.

Yeah, its a little high. I have run it at 900 and 1000, but the higher idle seems best for off idle acceleration.

 

[jumpinjan]

Every time I change the oil in any vehicle, I notice an increase in oil pressure.

 

[Nickodell]

The longer the oil is in use, the more water and gasoline it absorbs and the more the viscosity index extenders get used up. Add to that the lower flow resistance with a new filter (of course everyone with something between their ears replaces the filer along with the oil, right?) and you should get a slightly increased pressure.

 

[Alpine 1789]

That all makes sense, but I don't think I ever registered this high of idle pressure before, even with fresh oil. I didn't expect the change to the Rotella to make that much difference.