My oil pressure gauge is not pegged below 3000 rpm in highway cruise when ambient temperatures are very high (40 deg C). We do seem to get many really hot days this summer. When I get out of the highway into B roads (at lower speeds) or in the city things improve to the effect that the gauge pegs at 2000 rpm. Air conditioning is operational since no one could drive in this heat without AC. My engine was overhauled earlier this year and is running fine. At idle and in gear (auto box) I get around 10psi when engine is warm and full pressure when engine is cold. Car is a 280SL.
I am wondering if there is any reason for concern or if this behavior is normal and due to the very high temperatures. I have tried both 20-50W and 15-40W oil but I didn't see any noticeable difference. Has anybody else had similar experiences in such high ambient temperatures? Is what I see normal and I should not worry? My water temperature is around 85 deg C (185 deg
F) in these conditions versus 80deg C which I see when ambient temperatures are lower (25-30 deg C).
