Posted by John G. from NC on April 19, 01 at 10:01:28:
In Reply to: Need a quick response - rear differential fluid change posted by john on April 19, 01 at 08:51:52:
John,
I've got a '99 K2500/7.4L/3.73, and I had the same issue come up with the differential. No, you don't need "friction modifier," but according to someone here on the board (Ben or Traveler), it doesn't hurt anything if it gets added.
Sounds like some great preventive maintenance you're doing otherwise! I did major fluid replacements at about 40,000, although I didn't do synthetics. I'm planning to go with Mobil 1 ATF in the transmission and Mobil 1 oil in the differentials soon...some say it helps on the MPG just a tad.
Also a good piece of info with respect to the transmission -- I checked with Goodwrench.com on this; I plan to purchase a transmission pan for a 2001 K2500 Suburban, since it still uses the same 4L80E transmission, but the pan is already equipped with a drain plug. Then when I get Mobil 1 ATF and the filter changed, I'll have the shop change the pan for me. In the future, I'll be able to do the basic pan drop and filter changes myself by draining the ATF before pan removal without the hassle of the old "drop the pan and let the ATF go everywhere" scenario...
Of course, the standard disclaimer is that I will not be changing ALL of the fluid when I do that, but I'm more concerned with filter replacement, and as long as the fluid is replaced often enough, pan dropping instead of flushing is OK in my book.
Good luck!
John G. from NC