Has the six liter vortec. Has towing package. Boss just gave it to me to use for work. I'm looking it over tonight (always do that first thing with any vehicle I'm going to drive) and I have an oil pressure gauge that deflects all the way to to the right with ignition on (engine not running) and stays that way all the time when the engine is running. What is the likely cause for that? Also it is due for an oil change. How much oil, and what is recommended? Finally, pulled the trans dipstick and instead of pinkish red, I have pinkish brown. So I'm assuming it needs a change. Thoughts? Shifts smooth. 155k miles, not sure if it has been changed before or not. If it was, it would have been done under a Cadillac maintenance program -- boss said he tends to neglect things after the warranty expires (he is original owner). What trans is in it btw?