Had a scare some time into a 4 hour highway drive this past weekend, unloaded. At sustained higher RPM, say nearing 3000 my oil pressure gauge would drop. Factory gauge so gives indication of relative pressure but no numbers. Normally around O at idle and lower RPM, moderate to higher RPM in the MA range. Around 3000 RPM after 30 seconds to a minute it would go down to about O. I slowed down to keep RPM around 2700-2800 where pressure remained around MA as it normally is. After an hour or two it dropped again unless I stayed below 2400 or so. Slowed it down to 2000 RPM the rest of the way home where pressure remained where it usually is. Once off the highway oil pressure seems slightly now around N, ran normal and no abnormal noise.
Voltage remained a about 14v or a hair over. I've seen when alternator fails or voltage otherwise low the fuel gauge reads higher and all others read low... That was not happening, fuel level and coolant temp remained where they should be and no reason to doubt accuracy. Have run it at 3000-3500 sustained a time or two. Normally cruising around 3000 is no prob, and I've never sweated it as folks here say these engines were made to run on the governor all day.
Oil and filter had 6000-7000 miles on them due to my being busy, injured, and lazy. Changed oil the next day, was about 2 quarts short which it has been from time to time (leaks) with no abnormal pressure readings. I use Rotella T6 synthetic 5w40 and FL-1995 filters. Hot idle pressure was normal, normal pressure driving around that day but no sustained 3000 RPM. I know I need a real gauge, about to order one. Truck is currently out of commission probably through the weekend for unrelated reasons so cannot check for a few days at least.
Any thoughts on the oil pressure dropping at sustained higher RPM? Anyone seen a factory sender fail like this? Anyone seen low oil pressure at high RPM with these engines verified with an actual gauge?
Voltage remained a about 14v or a hair over. I've seen when alternator fails or voltage otherwise low the fuel gauge reads higher and all others read low... That was not happening, fuel level and coolant temp remained where they should be and no reason to doubt accuracy. Have run it at 3000-3500 sustained a time or two. Normally cruising around 3000 is no prob, and I've never sweated it as folks here say these engines were made to run on the governor all day.
Oil and filter had 6000-7000 miles on them due to my being busy, injured, and lazy. Changed oil the next day, was about 2 quarts short which it has been from time to time (leaks) with no abnormal pressure readings. I use Rotella T6 synthetic 5w40 and FL-1995 filters. Hot idle pressure was normal, normal pressure driving around that day but no sustained 3000 RPM. I know I need a real gauge, about to order one. Truck is currently out of commission probably through the weekend for unrelated reasons so cannot check for a few days at least.
Any thoughts on the oil pressure dropping at sustained higher RPM? Anyone seen a factory sender fail like this? Anyone seen low oil pressure at high RPM with these engines verified with an actual gauge?