Thought I'd pick your brains here, and see whether anyone can come up with something I failed to think of. I'm having an oil pressure issue on a freshly built engine (Ford 1600 XFlow). Running a dry sump system. I was tracking a car last year when oil pressure dropped off a cliff over the course of a lap. Pulled off and got a tow back into the paddock. Tested the sensor and established that it wasn't that, so we pulled the engine out and sent it off to be rebuilt. Bearings were stuffed. (that was a baaaad weekend) The engine was rebuilt and put back in the car. Ran it on the dyno and the exact same issue occurred (luckily, the bearings survived this time so it wasn't AS dramatic). Oil pressure is fine - until you get to about 80C oil temp. When oil is cold, it's perfect - it can idle at 70psi. As the oil temp increases, especially over 80C, oil pressure just suddenly starts to drop off rapidly - 5psi at idle and 25psi under throttle. Waaayyy too low. Running 20W-50 mineral oil as well, which is way thicker than I'd like to run. Swapped the oil pump, same issue. Pulled the engine again and the builder went through it again just in case they missed something, and said it actually looks perfect inside (glad there's no damage from the low oil pressure). So, it has to be related to the dry sump system somehow. But what could it be, which only occurs when the oil gets hot?? I've come across a lot of bizarre car issues, but damn, this one has us pretty confused. If anyone has any knowledge of dry sump systems, and/or has an idea, I'd be more than happy to hear it!! PS not sure if this is in the right section - if not, please move mods.