Hey guys.

I am going off to college in the end of August to Utica, NY, a good 3.5 hour drive from the Mid-Hudson Valley with one stop.

The Jimmy is in good shape but I am having weird oil pressure readings. Before the last oil change, I was getting 60 PSI at startup and 40 at operating temperature at idle and 0MPH. I would also get 60 at any speed and it would only drop as I stop to 40PSI.
At the last oil change, I requested 10W30 Valvoline Conventional oil put in the truck to last the rest of the summer. Some oil places forget what I ask them, so I put a label on the oil cap and on the radiator support next to the warning label for the airbag, coolant and starting fluids warning that says "10W30 OIL ONLY". Since my last oil change, I have been getting 60 at startup, but after driving about 10 miles, the pressure at idle drops to 30 in gear and a/c on when stopped, sometimes 25 PSI without a/c on and 20 if I cut the wheel. With it in park, it will stay at a constant 28-30. It also goes to 45-50 at the most at 65MPH. I was on the New York State Thruway at a constant 65 MPH and ~1900-2000 RPM for 2 hours straight without stopping going to college orientation last week and had consistent readings of the same pressures. Am I looking at a serious engine problem or could temperature have anything to do with it? I am getting this at 64F-84F over the past couple weeks. Am I looking at a faulty oil pump or an equally serious problem like a head gasket? I would not know why because I don't abuse this car in any way. The highest I have taken the engine was 3000RPM on acceleration to pull out onto a bad highway and I never take it near that point unless it is an emergency.

Also, here is a dumb question: What stuff should I have checked out that I probably can't do myself (like under the car stuff or complex stuff (NOT oil, coolant, brake fluid, power steering or ATF levels or tire pressure. I check those anyway often, at least once a refuel)) before I go to college to ensure safe, trouble free traveling? I know that Utica gets alot of snow in the winter, so that might be an important thing to keep in mind on my part when it comes to keeping it maintained.

(Just FYI on other stuff I had done already: The air filter is new and I had platinum spark plugs put in last year before I went to summer camp. The rear diff and transfer case fluid was changed 3,000 miles ago along with a new fuel filter as per the oil change place's recommendation. The front diff was changed a few months ago when they replaced the driver side CV axle. 100% of the ATF and the filter was replaced at 72,000 Miles at Aamco. I also had the power steering fluid changed at the last oil change. I had the idler arm and one upper ball joint that was wearing abnormally replaced a couple weeks ago.)

Also I learned something about the roof racks on these trucks. The crossrails are limp enough that when I pass 60-63 MPH on the Thruway, the new luggage carrier I got (see signature) with a 50lb bag of gravel inside as ballast (per instructions to keep at least 50 lb inside above 40 mph) shakes wildly enough it strikes the sunroof. I ended up buying 3 Titan 10' straps from Walmart, wrapping all 3 between the siderails and the top of the carrier to keep it low and secure. I ended up ziptieing all 3 hook sets together for safety so I dont have to worry about anything happening to the carrier or the top shell of it when I am going away to college. You guys can laugh out loud if you want, but I take safety very seriously. Also probably explains why I've never gotten pulled over or even so much as a parking ticket.

Thanks for any advice you guys might have and sorry for repeating certain stuff.

ComputernerdBD

 

Oil pressure fluctuation due to engine rpm is normal. Your figures sound perfectly safe. The old 'rule of thumb' is 10 psi for each 1,000 rpm.

 

I understand about normal fluctuations through engine RPM, but what about the decreasing numbers? Is it a sign of trouble? 20-30PSI at 500-550 RPM is alot different from the 40 PSI at 600RPM I usually get at idle. Could it just be summer temperatures? It's been 64-86F the past few days with no change. The coolant temp stays 1-2 notches below 210 even with 86F outside with no increase above that, so I know the engine isnt overheating and making the oil as thin as water.
Haven't had a Service Engine Soon light or Check Gages since Nov. 2007 just after we got it, so I know there isn't anything major right now going on.

Thanks