My oil pressure gauge jumps like crazy when at idle after the truck warms up. The idle is at about 600-650 rpms. When I hith the gas and raise the rpms to about 900-1000 rpms it stops jumping. I changed the iol pressure switch and it didn't do any good. I just changed the oil and used Amsoil 5w20 full synthetic high millage and a wix filter. I checked the oil level and it's where it is supposed to be. The manufacturer recomends 5w20 for the '02 ranger 3.0 but I have heard that with 189000 miles it might be a good idea to switch to a 30 weight oil. Any ideas or advice would be greatly appreciated.

 

Did you but a Motorcraft pressure switch or a cheaper one?
Sometimes "new" doesn't mean tested or good.

 

The problem with my 2002 Ranger 3.0, I replaced the oil presure sensor and that did'nt help. I then bought Amsoil Engine and Transmission Flush and Amsoil 5w30 full synthetic hugh mile oil, I have 159335 miles on the truck so I thought this would be the best thing for it. After using the flush as directed I put in the new oil and the problem stoped. It was 100 degrees outside today and after about 15 minuets on the freeway coming home it still stayed steady. Seems like the problem is solved.

 

I have the same with my 2002 Ranger 4.0. Have replaced it with a Motocraft and it does the same at idle. While not as bad as it was with the Carquest brand, still shows up after highway driving when engine idles. I'm thinking viscosity as well since the engine bearings are not as tight with high miles,