royal rear differential flush?
 

sup s2k fam,

I finally acquired a used diff replacement with unknown miles with the factory tamper mark still intact! :surprised: I'm excited & looking forward to not making v-tec noises in my car on jackstands & skateboarding everywhere! :argh: Just wondering if I should drain/fill the diff before I replace it, or should I install the diff first, drain/flush/fill (is using MasterPro GL-5 80W-90 ok?), let it run for a while (how long would you suggest in what conditions?), then drain/fill again (with Royal Purple 75W-90, Mobil1 75W-90, or Amsoil sever gear 75W-110?) Thanks in advance! peace :LOL:

http://www.redlineoil.com/product.aspx?pid=133&pcid=4

run redline. works great. I also used amsoil severe gear and it was good also. you only need 1 quart

I would definately drain it before you install it. You might find that you might not want to use it if something besides oil drains out.

Definitely change the oil ... as soon as you can. If it comes out clean, you can use your selected oil (Royal Purple or whatever). If it comes out looking nasty, use a cheap 80W-90 or 75W-90, drive the car for 1,000 - 2,000 miles and drain again before using the "real" stuff for 10-15,000+.

If I were using Red Line Oil in my diff, I'd probably choose this one:

http://www.redlineoil.com/product.aspx?pid=44&pcid=8

There is a very massive thread on S2000 diffs and oil in this forum. Search for it.

Turn it by hand many times at the stub axles to stir it up some. Once stirred up, drain the oil...it will most likely look dark and smell bad. If any large chunks come out or if the oil is heavy with metallic in it STOP, the rear will need some type of service or rebuild.
Once drained spray some brake clean inside and mix it around...drain once again. Let the rear stand with an open fill and drain plug for 10 minuets or use an air hose to dry the inside of brake clean. clean the drain plug and reinstall using a new crush washer.
Add fresh gear oil, I like the Amsoil brand best 75/110. The rear will hold a little less than a quart, don't over fill!! Reinstall the fill plug with a new crush washer, the rear is ready for install…..If you have any issues or questions you can PM me, good luck :)

This is what Mag-Hytec says to do:

1. Drain oil presently in the differential as completely as possible while the truck is still warm. This also helps remove contaminants and oxidized oil which can impair performance of LE gear lubricants. If contaminated oil remains in the differential, foaming can occur.
2. Do not use a volatile, chlorinated solvent or solvent-type flushing compound to wash out the differential. Any solvent trapped in the voids of the reservoir will cause corrosion. Also the presence of even a very little amount of solvent-type flushing compound will reduce the viscosity of a gear oil. Further, without a coating of oil for even a short time, rusting of internal parts of the differential can take place.
3. To properly flush the differential, use a light viscosity turbine oil or non-detergent engine oil (SAE 10 or 20). Jack up your truck (no-load condition) and run in gear for 15 minutes and drain. Note that some units can be so badly oxidized that physical removal from the inner surfaces may be required.
4. If new gears are installed make sure that the new gears that come with a rust preventative are cleaned off. This insures that any rust preventative, debris, metal chips and core sand is removed before installation.

http://www.mag-hytec.com/oil-1605DUOLEC.htm

I did this on a Suzuki Grand Vitara a few months ago using SAE30 non detergent because I couldn't find any SAE20. It was easy to do, but took some extra time. If it had a face plate type diff, I probably wouldn't have bothered.

Thats the procedure I followed when I switched to Amsoil 75W-140