Have you noticed that your C7 or C8 oil pressure is only about 37 psi while cruising down the road? Does that seem low to you?
It does to me, until I looked into it. Well, I’m still a little uneasy about it, to tell the truth.
The C6 used the LS series (port fuel injected) engines and the C7 and C8 (but not the C8 Z06) use the LT (direct fuel injected) engines. There were many, many detail changes between the LS and LT engines — including substantial changes to the oiling system.
There are a lot of reasons why an LT engine shows a somewhat lower oil pressure:
Thinner oil? My C7’s LT5 uses 0W-40 oil, my C6’s LS9 uses 5W-30. So the oil in the LT is thinner when cold but supposedly acts thicker when hot. So, this is not a clear explanation of differences in cruising oil pressure.
Oil pumps? The LS engines use a robust gerotor pump. The LT engines use a vane-type pump with a computer-controlled movable outer housing that provides variable pump displacement. In other words, the LT pump pumps less oil (less oil pressure) when cruising easily down the road. This reduces the power required to run the pump under most conditions. At heavy loads and high speeds, the pump housing re-positions and the pump pushes out more oil.
Oil pressure sensor? The oil pump is located at the front of both the LS and LT engines. Then all the oil goes to the back of the engine and through the oil filter. After filtration, the oil lubricates all the moving parts from back to front. In the LS engine, the pressure sensor is located near the rear of the engine just after the filter. In the LT engine, however, the pressure sensor is relocated to the front of the engine. So, in the LT, the pressure is measured after all of the ‘leaks’ out of the cam bearings, crank and rod bearings, pushrods and rockers, and the oil squirters that cool the bottom of the pistons. So, for a given oil pump output pressure, the LT pressure sensor will indicate a significantly lower pressure than an LS sensor.
The net result is that the oil pressure of an LT engine will read about 7-10 psi lower than an LS engine.
For me, it’s hard to get used to.
There’s a great web page that provides more info and some great illustrations: https://www.corvette-web-central.com/LT1oilpump.html