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oil weight and presure?

Discussion in 'Jeeps' started by misanthrope, Feb 2, 2007.

  1. What weight oil do you guys use in winter, and in summer? My book only states SAE approved oil, no specific weight. I'm running 10-30 now. Also what is your oil pressure during idle? Mine drops to 20psi 40 cruising. I'm not use to seeing PSI drop to 20. this is my first jeep. My Chevy's always around 40 idle.

    It's a 98 TJ
  2. payton

    payton Senior Member
    Messages: 470

    thats not unnormal for a jeep. you could jump up a size dont go too thick or it will over work the motor. one of my yjs would idle around 11 psi. and was fine. it would start lifter tapping around 8psi. but i was soon to blow that motor..no not due to oil pressure.. due to 35in tires.- dana 60s 538s.. rs44044 with soa. anyway i thought i would walk this water hole. well it got thristy and took a huge drink.

    but 20 psi wont hurt anything but if your worried jump up a bit.

  3. sefh

    sefh Senior Member
    Messages: 439

    I have an 86 CJ7 and a 99 F-250 V10 and I run 5W-30 in both year round. Your oil pressure sounds right. All Jeeps are tempermental and kinda all do their own things. Do you plow with it?
  4. ....

    Yup have had it for a year....the tranny leaks, I have a warranty but it does not cover leaks....only failure....which is crazy ......this leak will lead to failure and they will have to fix it. I'll remove the plow frame of coarse before they inspect it. I've been topping the fluid with Lucas tranny fluid and leak stopper. Seems to lose about 4oz of fluid never any more then that, i know to top it off when she slips a bit. Other funny thing i does sometimes is hesitate from park to reverse, then stall going from reverse to drive. I've replaced the fuel pump which has helped. I think it all points tio the tranny. Who knows....
  5. Donny O.

    Donny O. Senior Member
    Messages: 410

    I think mine would go down to about 30 at idle, but not totaly positive on that. just remember the factory guages on most vehicles are glorified idiot lights and not very accurate, but will show if soemthing goes wrong. if you are worried about your actually preasure then connect a real aftermarket guage and check it.
  6. bdhunter

    bdhunter Senior Member
    Messages: 158

    The old Cherokee was leaking tranny fluid a few months ago, and it turned out to be where the cooler lines connect in. Seems there are little pieces of plastic like things that are prone to leakage after some age. Had em replaced, and Viola! not a drop of leakage now!
  7. fast68

    fast68 Junior Member
    Messages: 17

    they say either 4 or 7 psi per 1000 rpm is normal

    i forget which but im pretty sure its 4psi and that im thinking 7 because thats 7-9psi for fuel pressure on most of the old carb mechanical pumps

    30 at idle is crazy insane good

    probably innacurate

    good luck
  8. You had a tranny shop do it or a regular mech?