Oil weight and pressure relation

PapaBear · 08-17-2012, 09:57 AM

Guys, time to be serious lol. Here's the backstory:

I've always run 10w30 Mobil 1 in this new motor, and always have seen above 25psi oil pressure at hot idle. New cam went in with a GM performance parts oil pump and 5w30 mobil 1, and initially saw about 30-35 psi at hot idle. I drove truck back from NC and all has been well.

This morning, while on the way to work at a stop light, I saw it dip as low as 12 psi at ~800 RPM idle, but it picked right back up. Book says ~10psi per 1000 RPMs is good, but I know it should be higher with this pump.

Is it possible for an oil pump that's brand new to fail this quickly? I would have to rule out the O-ring in the pickup tube based on the initial numbers, so don't know where to point other than the pump or the oil weight.

Any suggestions? Switch to 10w30 or 10w40 and see what happens? Or proceed to tear it apart and go with a different pump? Usually this pump performs on par with Melling blueprinted pump, which is the reason I went with it due to wait time on the Melling I initially wanted.

08-17-2012, 09:57 AM	#1
PapaBear Senior Member Join Date: Aug 2010 Posts: 2,809	Oil weight and pressure relation Guys, time to be serious lol. Here's the backstory: I've always run 10w30 Mobil 1 in this new motor, and always have seen above 25psi oil pressure at hot idle. New cam went in with a GM performance parts oil pump and 5w30 mobil 1, and initially saw about 30-35 psi at hot idle. I drove truck back from NC and all has been well. This morning, while on the way to work at a stop light, I saw it dip as low as 12 psi at ~800 RPM idle, but it picked right back up. Book says ~10psi per 1000 RPMs is good, but I know it should be higher with this pump. Is it possible for an oil pump that's brand new to fail this quickly? I would have to rule out the O-ring in the pickup tube based on the initial numbers, so don't know where to point other than the pump or the oil weight. Any suggestions? Switch to 10w30 or 10w40 and see what happens? Or proceed to tear it apart and go with a different pump? Usually this pump performs on par with Melling blueprinted pump, which is the reason I went with it due to wait time on the Melling I initially wanted.