I finally got around to changing the dif oil to synthetic in my S10. Last year, I pumped it out and replaced it with SuperTech 80W-90 as a flush. (see the thread I started "Changing the differential oil without removing the cover", or something like that). Vehicle is a 1992 4.3L, 3.08 7.5 inch rear end, 31K miles.
Some observations and musings
1) No magnet present! There is a dimple on the old cover where a doughnut magnetic should be, yet no magnet was found anywhere (see pictures). The new cover did come with a doughnut magnet, but it was lacking the dimple! It was also a very weak magnet, so I used one from an old hard drive instead. I didn't put this on the cover, but the base, in the valley under the pinon.
2) No "white slime of death" present. If there was no magnet to catch the break-in metals, and no residue, it seems likely that most of the wear metals did indeed get pumped out with the first change, when the cover was not removed. (before doing the drains, I drove for about 15 minutes to stir things up)
3) The SuperTech oil I used for a flush only had about 1K miles and less than a year on it. It looked to be in very good condition, nice and clean, which I would hope after such a short period. However, it looks like there could be some foaming going on. Since I'm not an expert on these things, see the pictures and decide for yourself if that is true "foam", or normal.
So, no magnet, no white slime found, and factory fill first replaced after 17 years and 30K miles, yet everything looks good. The Amsoil Severe Gear 75W-90 might be overkill, but this rear end should now last a LONG time.
Some observations and musings
1) No magnet present! There is a dimple on the old cover where a doughnut magnetic should be, yet no magnet was found anywhere (see pictures). The new cover did come with a doughnut magnet, but it was lacking the dimple! It was also a very weak magnet, so I used one from an old hard drive instead. I didn't put this on the cover, but the base, in the valley under the pinon.
2) No "white slime of death" present. If there was no magnet to catch the break-in metals, and no residue, it seems likely that most of the wear metals did indeed get pumped out with the first change, when the cover was not removed. (before doing the drains, I drove for about 15 minutes to stir things up)
3) The SuperTech oil I used for a flush only had about 1K miles and less than a year on it. It looked to be in very good condition, nice and clean, which I would hope after such a short period. However, it looks like there could be some foaming going on. Since I'm not an expert on these things, see the pictures and decide for yourself if that is true "foam", or normal.
So, no magnet, no white slime found, and factory fill first replaced after 17 years and 30K miles, yet everything looks good. The Amsoil Severe Gear 75W-90 might be overkill, but this rear end should now last a LONG time.
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