My first indication that there was something radically wrong was when I glanced at the instrument cluster of my C5 after turning the key to "on"-before starting the engine-lo and behold, both the analog oil pressure gauge and the digital readout on the cluster said my oil pressure was a whopping 73 PSI-and the motor wasn't even running. Obviously, something was grievously amiss under the hood, and my first suspicion was that the oil pressure sending unit had given up the ghost.
Upon doing a bit of research on the Internet, my initial diagnosis proved to be correct; apparently, this early-death syndrome of the oil pressure sending unit was a fairly well known and not-too-rare occurrence with '97-'99 C5s. From what I read on forums, blogs, and other sources, some other owners with the same affliction simply opted to drive their C5s as-is without fixing the problem. While this is indeed the easy way out, if something else should go awry with the engine, you won't get any early indications without a proper-functioning oil pressure system. Nope, that's not for me; my credo is simply that if it's broken, then fix it.
If you elect to have the work done by the local garage, be prepared to spend between $150 and $200 for the job, plus the price of the sending unit (about $20 additional); or do it yourself and pocket the cash. Here's what it takes to do this job. here.
Time: about 3 hours
Tools: sockets, swivel socket attachment, screwdriver, wrenches, pliers, lock-grip pliers, torque wrench
Intake Manifold Bolts (First Pass in Sequence) - 44 lb/in
Intake Manifold Bolts (Final Pass in Sequence) - 89 lb/in
Fuel Injection Fuel Rail Bolts - 89 lb/in
Throttle Body Bolts - 106 lb/in
Oil Pressure Sensor - 15 lb/ft
Engine Wire Harness Clip Bolt - 37 lb/ft
Engine Wire Harness Ground Strap Bolt - 37 lb/ft