Synthetic gear lube and leaking seals

Discussion in 'Transmission & Driveline Topics' started by tom3, Jul 13, 2005.

  1. tom3

    tom3 Veteran Member

    Aug 1, 1999
    Put Mobil 1 in both Camaro rear ends last summer, a 70 and an 88. While the cover was off I pulled the axles and put in new axle seals then. Had to replace the pinion seal in the 88 last month, replaced both axle seals in the 70 yesterday and the pinion seal is leaking a little too, and I just looked at the 88 and there's drop of oil on the backing plate, it's leaking already too at the axle. Have to figure this lube is probably not worth the trouble, time, and money. Figure I've spend about a hundred bucks on lube, seals, and cover gaskets. Hate to just drain it out and put regular lube in but that's looking like the way to go.
  2. COPO

    COPO Veteran Member Lifetime Gold Member

    Sep 15, 1999
    Ontario, Canada
    The pinion leak could be getting by the groove that the pinion seal made from the drive shaft turning after so many years. You can buy a plastic sleeve for the pinion. I know other guys that are using synthetic gear oil but I don't think I would. It's like the Muncie tranny. Your not really suppose to use GM syncomesh trans fluid on Muncies because it's thinner than 80w90 gear oil. GM syncomesh trans fluid should only be used on late models after the Muncie. The Muncie needs 80w90 gear oil.

    I'd be dumping the syn gear oil back in the container and use it for oiling. You need to refill with 80w90 non syn oil. Sounds like the oil is too thin and too slippery.

    Mark D
    1970 Z28
    WTB: 70 SS396 Chevelle 4-spd, flapper hood car, no rag tops, 1-2 owner car.
  3. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    I have been running Amsoil 75w90 synthetic gear lube in all my rear ends for almost 20 years with no problems or leaks. I also use in my Muncie 4 speed in my Camaro and also in the clunky Muncie truck 4 speed in my Chevy pickup. This stuff is designed to replace the non-synthetic gear lubes and works just like the original stuff, but you get the advantages of synthetic. The Mobil 1 I've seen isn't a gear lube, and it shouldn't be used as a gear lube.
  4. tom3

    tom3 Veteran Member

    Aug 1, 1999
    Bottle says GL5 for hypoid differentials and manual transmissions, but if I see one more drop of oil, I'll be takng COPO's advice. Almost nine bucks a quart for nothing but trouble. The Amsoil might be a better product but it's nowhere around here.
  5. big gear head

    big gear head Veteran Member

    Jul 30, 2001
    Central City, Ky.
    Are you using sealant around the outside of the seals before you drive them in? Are you putting some grease or oil on the rubber lip of the seal before you put it back together? Did you put some sealant in the splines inside the yoke before you put it back on? There are lots of reasons that seals leak. I have never seen one leak because of synthetic oil. I have been using Amsoil in all of my cars and trucks for over 8 years now with no leaks caused by the oil.

    Byars Performance LLC
    High Performance Drive Train Parts And Service
  6. tgw323

    tgw323 Veteran Member

    Jun 25, 2000
    Roanoke, Ind.
    I had trouble with Red LIne leaking at the pinion seal. Just a little bit of auto trans sealer seemed to take care of it.
  7. GoldenOne7710

    GoldenOne7710 Veteran Member Lifetime Gold Member

    Jun 23, 2004
    Athens, GA
    For the record. Synthetic libricants of ANY form or fashion DO NOT CAUSE LEAKS. However, if you use sythetics in stuff where there are ALREADY leaks, yes it will leak faster. This is only because of the greater flow characteristics of sythetics. So if you have a leak period. Fix it. It done right, the leak WILL NOT come back any time soon. Not pointing fingers at anyone specific by the way. Just trying to educate.

    Objects In Mirror Are LOSING
  8. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member


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