G'day guys! I was wondering if anyone have an idea what's wrong with my I6. Today was a very hot day here in Western Sydney. As I was driving my 95 EF (mid-day), I noticed my oil pressure gauge was giving a very low reading...and when idling, it would go to the orange region and at one point gave off a beeping sound indicating very low oil pressure. This has been the second time it has occured, I ignored the previous one because it never happened again (on that day). I remember it was a very hot day (40degs) as well when it first happened. At these instances, my water temp reading is fairly normal...pointing at the letter 'M'. I am using 10-40W viscosity engine oil. This only happens when ambient temp approaches 40 degs.

Any ideas? Is it the engine oil? The heat? My oil pressure sender failing (in the heat)? Please help! Thanks in advance.