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What's the best oil for my engine? 1999 grand Cherokee 4.0L

Discussion in 'Cherokee' started by ShakyShane, Aug 29, 2019.

  1. Aug 29, 2019 at 5:50 PM
    #1
    ShakyShane

    ShakyShane [OP] New Member

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    Michael
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    1999 Jeep Grand Cherokee Lerado 4.0L
    Bigger tires p255 r16
    Ok so I bought my grandpa's jeep he retired years ago and let it sit for awhile. It is a 1999 jeep grand Cherokee lorado 4.0 4x4. 136,000 miles on it when I got it. It's at 138,680 miles now. I took my grandpa's advice and decided to put Castrol GTX 10w30 which is what he always used. No oil leaks or burning of oil. I check the stick once a week. Stays on full. I replaced the idler pully tensioner pully and this weekend I'm putting a new thermostat and water pump on it. Anyway I'm asking about the oil. I feel like if what's working works then that's great. But synthetic has me thinking. I use mobile one filters.

    20190820_185403.jpg
     
    spyder62 likes this.
  2. Aug 29, 2019 at 6:12 PM
    #2
    JKBob 25

    JKBob 25 Well-Known Member

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    Jersey Shore, NJ
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    Welcome to the forum @ShakyShane .
    Synthetic oils wont hurt your motor. If you decide to go with one. Use the same weight the manufacture recommends. But the Castrol 10 w 30 is fine for your GC. Have fun with the forum. Buncha great people here. :jeepwave:
     
    aggrex and ShakyShane [OP] like this.
  3. Aug 29, 2019 at 6:17 PM
    #3
    Awrench

    Awrench Well-Known Member

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    watch out for the hype..
     
    Last edited: Sep 1, 2019
    aggrex and JKBob 25 like this.
  4. Aug 29, 2019 at 6:41 PM
    #4
    aggrex

    aggrex Well-Known Member

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    DE
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    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Welcome @ShakyShane ....Looks like your grandpa had a well maintained JGC. You're taking the right steps in vehicle maintenance. I'm using Pennzoil synthetic oil / PurolatorOne filters in my vehicles. Walmart everyday low prices keeps costs reasonable. Oil+filter change intervals @5000-6000 miles and air filter @12-15K. Regular Dino Castrol GTX is a fine choice. Just follow recommended oil viscosity and you probably don't need to check it weekly if it seems to be consistent between oil changes.
     
    JKBob 25 and ShakyShane [OP] like this.
  5. Sep 5, 2019 at 11:47 AM
    #5
    Prerunner1982

    Prerunner1982 Well-Known Member

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    Many Jeepers with 4.0s recommend RotellaT as it is supposed to have higher concentrations of Zinc which are good for a flat tappet engine like the 4.0.
    I currently run Valvoline 10w30 or Valvoline High mileage synthetic blend on my recently freshened up 4.0, she runs quiet.
     
    JKBob 25 likes this.
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