Is it OK to put synthetic gear oil in my front differential?

Discussion in 'General Chevy & GM Tech Questions' started by Rancho5, Sep 5, 2008.

  1. Rancho5

    Rancho5 New Member

    I drained my front and rear differentials (100k miles) and refilled each with Mobil 1, 75-90w.

    I looked around on-line and found a Chevy booklet. It said that it's alright to use synth in the rear, but didn't say if it was alright for the front.

    Is it?
  2. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    my only thought is that maybe because it sits for so long and actually isnt moving around like the rear all the time that it needs something heavy to keep it properly lubed for when you finally do through it into 4WD
  3. Rancho5

    Rancho5 New Member

    So dinosaur gear oil is heavier than synthetic? I've never heard that before. The front specs say 80-90w and the rear 75-90w. Autozone's computer said 75-90w in both. Since I couldn't find any 80-90w for the front, I just used the 75-90w figuring it would be alright.
  4. collinsperformance

    collinsperformance Epic Member 5+ Years 500 Posts

    yes you can add syn oil in the front diff---the only issue is the diff if it has a LS (Limited Slip) you need the friction modifier.......mike
  5. Rancho5

    Rancho5 New Member

    How do I check to see if has LSD? On my sports car you jack up the back and spin the tires. When both move you have LSD. How do you check it on a 4x4 burb?
  6. collinsperformance

    collinsperformance Epic Member 5+ Years 500 Posts

    look at the spec tag on the door jam and or glovebox. you can do the same test you said to see and the fail safe method pull the rear cover and look. you are going to replace the oil anyway......mike

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