Ok, I changed the oil/filter today. Took it in and had the transmission fluid flushed, and I also changed the front/rear diff fluid. Drove the truck about 10 miles on the highway, then pulled off and was going through stop signs. I noticed the *OIL* pressure was at the 30 bar and as I accelerated, it would boost steadily with the throttle to above the 60 bar and drop down when the transmission shifted. I pulled over. When parked, the oil pressure was still doing it. In reverse I didn't notice it, but if I drove forward, however, it would do it again. There was a odd almost ticking noise from the passenger lower side of the motor...roller? It was from below the compressor. What is the cause of this? 5mins later it was driving fine and the oil pressure sat at around the 45 bar. Is this a sign that the oil pump is going out? I thought a faulty oil pump would cause a drop in oil pressure. The oil level is fine, and oil is new...I'm stumped. Oh, another thing...the speedometer was flickering at around 10mph when it was doing this.