I have a 97 Ranger with a 2.3liter 4cy engine. It has about 77k miles on it. Just a few days ago I noticed the oil pressure gauge would go from normal down to low whenever I would accelerate after comming to a complete stop. Ater I hit about 15mph the gauge jumps back up to normal. It starts to do this after about 10 minutes of driving. I also only use synthetic oil. I would appreciate any ideas of what the problem could be? Thanks.

 

Is it full of oil?? I know dumb question but I gotta ask.

 

Assuming the "oil pressure gauge" you refer to is the thing that came with the truck mounted in the dash, then what you likely have is an oil "idiot" gauge. For years these things have been set up to indicate two conditions, either above or below a set pressure, maybe 7 psi. It is either on or off. I went thru three senders and my "gauge" still would go all over the place at times. Yesterday I installed a real mechanical oil pressure gauge and am very happy with it. A real gauge, once the engine is warmed up well, will read lower at idle and jump up when you blip the throttle (makes sense since the pump turns with the rpm). Mine, when hot runs 17 psi at idle and 42 psi at cruising speed (2000 rpm). Get a real gauge and cast out all doubt.