Hello! Is synthetic fluid ok in front diff? 93 K1500

Discussion in 'General Chevy & GM Tech Questions' started by SumB, Mar 7, 2014.

  1. SumB

    SumB New Member

    First off hello to everyone! I was waiting to get my new to me 93 K1500 all fixed up before posting some pics and introducing myself but ran into a question I am unsure about.

    As the title asks: is synthetic gear oil ok in the front diff of my '93 K1500? I picked up some Valvoline 75w90 synthetic but have read it may cause a leak. Any experience or advice is greatly appreciated!
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    some say that changing to synthetic will cause leaks because of conditioners in the oil that swell seals. I have always run synthetic in my trucks, even if I buy them used with high mileage I still switch to synthetic. I have not seen any leaks develop. knock on wood!!
    Last edited: Mar 7, 2014
  3. SumB

    SumB New Member

    Thanks Pikey, I have also heard that too. But the reasoning on this was a little different. I read this model of truck the front diff was manufactured without a gasket and the synthetic might eat the sealant.
  4. j cat

    j cat Epic Member 5+ Years 1000 Posts

    the use of silicone sealers they say is attacked by the synthetic gear oil...you will find silicone sealers saying that this sealant will not be damaged with synthetic gear oils... most of the older silicone sealants are damaged and then it will leak... I would use the 80-90 wt for the front diff.. or what ever your vehicle manual states is the correct product...
  5. SumB

    SumB New Member

    I will not risk it then, thanks j cat
  6. Cowpie

    Cowpie Rockstar 3 Years 500 Posts

    Early on when synthetics first showed up in the marketplace, there was not any additives similar to regular oils that helped prevent leaks from seals. That got rectified quickly. There is hardly an application today that couldn't work with synthetics. I have used synthetics with RTV sealers and never had a problem.
  7. Jamm3r

    Jamm3r Member 2 Years 100 Posts

    If you have a 93 that's never had front axle work then it doesn't need a reason to start leaking. I run synthetic in my 97 because of the potential for bearing and gear damage with Dino oil at the low temps we have here

Share This Page

Newest Gallery Photos