Rear Carrier Seal Leak

[Whiplash Willy]

A few months ago, I changed my rear diff fluid at 15k miles with Amsoil 75w-90 Severe Gear Oil. I filled it on a flat surface until fluid started dripping out of the fill hole, so I am sure I got the level right.

A few weeks later, I noticed a small amount of diff oil around the rear diff carrier seal. I am guessing the thicker oil caused extra pressure to build up, and blew oil past the seal. I have since cleaned up the area, and not noticed any more oil seepage in that area. If oil blows past the rear diff carrier seal due to excess pressure, does that mean the seal has been damaged, and needs to be replaced, or should I not worry, since I have seen no further sign of a leak?

 

[1engineer]

A few months ago, I changed my rear diff fluid at 15k miles with Amsoil 75w-90 Severe Gear Oil. I filled it on a flat surface until fluid started dripping out of the fill hole, so I am sure I got the level right.

A few weeks later, I noticed a small amount of diff oil around the rear diff carrier seal. I am guessing the thicker oil caused extra pressure to build up, and blew oil past the seal. I have since cleaned up the area, and not noticed any more oil seepage in that area. If oil blows past the rear diff carrier seal due to excess pressure, does that mean the seal has been damaged, and needs to be replaced, or should I not worry, since I have seen no further sign of a leak?

If it was purely a heat induced pressure rise you should be OK.
Questions:
1. Why not OEM fluid?
2. Changing at 15K?

I have learned, sometimes the hard way, that OEM specs on interval and lubrication are absolutely the best for general use. Now, if you are running Rubicon on a daily basis or something then there are better intervals and specialty fluids out there.

 

[Whiplash Willy]

If it was purely a heat induced pressure rise you should be OK.
Questions:
1. Why not OEM fluid?
2. Changing at 15K?

I have learned, sometimes the hard way, that OEM specs on interval and lubrication are absolutely the best for general use. Now, if you are running Rubicon on a daily basis or something then there are better intervals and specialty fluids out there.

Thanks 1e...that is what I figured, but it is always nice to hear from others as well. If I don't see any more leaks, any my level is good, I will just stop worrying about it.

To answer your questions:

1. I get a discount on Amsoil products, and they, as well as most other brands, don't offer a 75w-85. Toyota's Genuine LT 75w-85 Diff Oil is about $30/qt, vs Amsoil SVG's $11/qt. Many people have used 75w-90 in place of 75w-85 without any documented issues. Basically I believe the Amsoil is a better product, that I will be able to run at higher drain intervals, for 1/3 of the price of the OEM Toyota stuff. I also believe the main reason Toyota moved over to the thinner 75w-85 is to improve fuel economy, not to offer better protection.

2. It really isn't documented anywhere at what mileage you should change your rear diff fluid. Toyota just recommends periodic "Inspection". I checked it at 15k, and it was dark grey, and had a bunch of "grey paste" on the magnetic drain plug. With all of the metal particles in there from the initial break in, I figured it wouldn't be a bad idea to change it.

Amsoil SVG may be a little over kill for my application, but for $11/qt, I might as well use some of the best stuff out there.