Just got the wife a '99 Cadillac Catera. The car is in good condition and runs well. It has 82,000 miles and I finally decided to give ARX a try, but I noticed that when the engine is warmed up the oil pressure fluctuates wildly from around 20psi at idle in gear to a maximum of maybe 45 psi when you accelerate and then at moderate speeds the oil pressure goes down to around 30 psi. What concerns me most is the low pressure at idle sitting at a light. Do I have a bad oil pump? Can ARX help a situation like this? What causes oil pressure to fluctuate so much? Can I really even rely on the oil pressure guage?