: Notes on my diff fluid change

10-21-11, 08:26 PM
this is mostly a repost of my other thread, so I apologize if some think it may not be needed, but I figured this title might popup in more searches directly related to changing the diff fludi, I had to search for a for this information for a while, so here it is condenced into a single post.

1) the car must be level--- the stands *must* be centered on the pinch-welds to do this, preferably with the same number of notches between the top and bottom portions with identical jacks. Failure to have the car level *will* create an over/under filled situation(over if the front is lower, under if the front is higher than the rear). You should be checking this with a level on the same pinch welds (the one closest to the side skirts) and it should be in the middle within a degree or so.
2) the correct amount of fluid is 1.3-1.4 quarts, if you're able to put more than this in there(in the relm of 1.6+), the car is not level.
*3) Additive is necessary, it however is *not* necessary to add the entire bottle. Amsoil states 2.4 ounces for drain and fil via plug, and 3.4 ounces for a breakdown and re-build where all the fluid is extracted using their oil that has additive already. This follows with the theory that since their products and similar GL-5 oils already have additive, that it's not necessary to add the full 4oz. It could be debated as to whether the additional 2oz or so is enough to cause the LSD to slip too much and cause traction loss , as well as the other problems that too much LS additive introduces; such as decreased resistiance to heat and increases in oxidation rates for the oil, however the general concensus from what I've seen from people that have acutally quoted data or sources is; use as little as is required to eliminate chatter and too-much will reduce your LSD's abilities.
4) Even though my diff was correctly filled, the magnetic drain plug was COVERED with metallic debris @ 5,500miles-- at this point I wish I had changed it sooner.
5) there is a small sensor plug right next to the main drain plug, I did not remove this one to drain/refill, and it is not necessary to.
6) If level and if your car is correctly filled with fluid, your fill-plug should seep a very small amount of fluid (1 drop per minuite or so)
7) the new part number for the Diff additive is 88900330 the cost is $12.54 full retail.

*this is currently purely based on amsoil's site, and may change if I experience chatter with aprox 2.2oz of additive on Mobil 1 LS fluid.