I hit 190,000 on my last road trip on my 09 6.0 Burb and just cannot get over the low oil pressure. 30psi at 70-80 mph cruise and 39psi tops when hitting passing gear. I idle at 19-20 psi warmed up. It went down a couple psi after switching partial synthetic a couple oil changes back. Everything is smooth but it is still strange to me I guess I have always been used to bigger numbers.

 

This is my oil pressure as we were approaching the Eisenhower Tunnel on I-70. This was just about maximum stress on the engine - 14,500 lbs going up 6-7% grades. Pressure is sitting at 40 PSI. Engine has 130k on it.

Don't worry about it.

 

Though many people strongly believe in the Synthetics, you could change back to a Multi-Viscosity (like a 20w-50w) and that may help some.

 

Thank You Gentlemen for the replies.

 

general rule of thumb out of my engine rebuilding textbook; minimum oil pressure should be 10psi for every thousand rpm.
the oil warning pressure light probably comes on at 4psi or below.

 

I had really low oil pressure on my 2007 Suburban (112000mi), but a can of Seafoam and an oil change 125 miles later fixed that. My vehicle has a valve screen right in front of the oil pressure sending unit (5.3 Flex) that gets clogged (you'll find other posts discussing this issue) especially as the gunk accumulates. My vehicle went from having the oil light on (less than 5 psi) to 50-60 PSI at highway speeds and 40 psi at idle. My new-to-me 2013 Suburban (9400 miles) idles around 40 psi and is at 50-60 psi at highway speeds.