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Changed LSD oil out to synthetic (and used LSD additive)...now rear is binding

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#1 · (Edited)
I changed my LSD oil out a little over a week ago with Mobil 1 75w90 synthetic and I also put some LSD additive in as well (the oil I had was Mobil 1 75w90 and not Mobil 1 LS 75w90).

My rear differential is now binding if I make any sort of turn just after start up (when the truck has been sitting over-night) and it stops doing it after I have driven about 1/4 mile.

I remember reading somewhere (I think in my owner's manual or other paperwork that came with my truck) that Toyota recommends using mineral based gear oil w/ an LSD additive for use in their Limited Slip Differentials instead of synthetic gear oils.....but now I can't find where I read that.

It's kind of a pain because I can't find any non-synthetic 75w90 gear oil in any stores around here......I'll probably end up ordering some from somewhere soon because this is getting annoying and I don't want to damage my rear differential.

Has anyone else had this problem?
My truck was not doing this before I changed out the LSD oil with a synthetic, and I checked and their are no leaks in the rear differential.

Is it possible that Mobil 1 75w90 oil is really their LS 75w90 oil and they just don't have it marked on their packaging? If this were the case than the rear could be bind due to over -lubrication. However, the fact that this goes away after about 1/4 mile and only happens when the truck has been sitting for more than 12 hours leads me to believe the the synthetic oil is having problems "climbing" the gears in the differential when it is cold.
 
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#3 ·
x2...I used Mobil1 when I changed mine and added a tube of the BG limited slip additive I picked up from Koons in Tysons (since you are in the nova area). I did it about 7k ago and have not noticed anything.
 
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#6 ·
You might not have added enough Friction Modifier. When I switched my rear LSD out I also used Mobil 1 75w-90 but I had to add a entire tube of Trans-X LSD Friction Modifier from Autozone as thats what it said on the package. Good news is that I have no chattering or anything at all. The Rear LSD is working smooth as glass.
 
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#7 · (Edited)
Thanks for the responses guys. I am going to add another tube of Trans-X LSD Friction Modifier (which is what I used initially) tonight to see if that works . That's the cheapest/easiest route to start out with....if that doesn't work than I'll completely drain it and put some non-synthetic gear oil in there.

I was able to get about 3.4 quarts of gear oil in my rear diffential using my syphon pump, so perhaps that extra bit of oil has stretched the tube of LSD friction modifier that I used just a little too thin to work properly. Has anyone else had to use two tubes of friction modifier??
 
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#9 ·
I could not get the Mobil 1 in mine to stop binding. I finally went to Royal Purple and have no more problems. Even with the friction modifier Mobil 1 did not work for me.
 
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#11 ·
It's like a groan coming from the rear of the truck usually when the rear diff is cold (after about 4-5 hours sitting). I think the Mobil1 is too light and does not do a good job of clinging to the clutches. Once you get it turned over a few revs it's fine.
 
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#12 ·
I changed my LSD fluid over to Mobil1 at around 25,000 and added a tube of LSD friction modifier. Several weeks later, the differental developed a very loud and pronounced howl at highway speeds. I drained the fluid and replaced it with standard gear oil, again using the modifier. Unfortunately, the howl never went away and the dealership had to replace the ring and pinion gears under warranty. I don't know if the gear set would have gone out regardless of using Mobil 1, but all signs are pointing in that direction. Mobil makes very good products but I'd be very cautious about using their synthetic gear lube in an LSD differential!
 
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#13 · (Edited)
I just put another tube of Trans-X LSD Friction Modifier in the rear differential. I took it for a quick spin and it seems to be very smooth, however the true test will come tomorrow morning after it has been sitting all night. I'll post what happens tomorrow.....if it is still binding at all I will be ordering some new gear oil ASAP (all the stores around here only have Mobil 1 75w90).

My truck only has 15,000 miles on it, and since the factory powertrain warranty is good until 5 years/60,000 miles I'm not too worried.
 
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#14 ·
Mine did the same with the Mobil 1 75W90. It did it all day long though, not just after sitting long periods. Only noticed it at slower speeds and tight turns (parking lot). That night I drained a little and put in the friction modifier and it instantly went away.
 
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#16 ·
Well, after adding a second tube of LSD friction modifier to the rear and letting it sit overnight my LSD is not binding anymore. In fact, it is very smooth.....even after sitting all night.

Since everything is working good now I am not going to change my LSD oil out now. So, for all those other people who are having the same problem as me with Mobil 1.....just use 2 tubes of Friction Modifier instead of 1 and that should solve any binding issues.
 
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#18 ·
2 tacomas said:
Well, after adding a second tube of LSD friction modifier to the rear and letting it sit overnight my LSD is not binding anymore. In fact, it is very smooth.....even after sitting all night.

Since everything is working good now I am not going to change my LSD oil out now. So, for all those other people who are having the same problem as me with Mobil 1.....just use 2 tubes of Friction Modifier instead of 1 and that should solve any binding issues.
Click to expand...
What is it doing?
 
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#21 ·
Back in the dark ages (pre-synthetics), we would sometimes get noises from limited slips in turns, The fix was to find an empty parking lot and make several full lock turns in both directions to work the lube into the clutches. Don't know if it will help with this new stuff, but it wouldn't hurt it.
 
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#22 ·
cj99si said:
I mean is it dragging a tire, grinding.....
Click to expand...
The rear differential would make a groaning noise and you could also feel it as well (the rear would vibrate slightly). It would happen whenever I made any sort of turn within the first 1/4 mile or so after the truck had been sitting for a long period of time. For whatever reason I had to add a second tube of friction modifier to get it to stop....it now seems to be working nice and smooth.
 
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#24 · (Edited)
The binding is back...and worse than before

Well,

About 2 months and 3,000 miles after switching to Mobil 1 synthetic in the rear differential, my LSD starting binding really bad again last week. It was so bad that at first I thought I was dragging something....both myself and my fiancée jumped out of my truck and looked underneath the truck to see if I was dragging anything. The binding was A LOT worse than what it was doing last time and the LSD started binding anytime the truck was stopped for more than a minute or so (not just after sitting for long periods like last time). It would continue to bind for as far as a 1/2 mile. The worse part was I on vacation at the beach last week and didn't have anywhere I could change out the LSD oil...so I had to drive around with it binding all of last week.

I was able to find some non-synthetic Valvoline 80w90 gear oil yesterday so I put that along with a bottle of LSD friction modifier into the rear differential and the binding went away instantly.

I am fairly sure that the damage has been though and it's just a matter of time before it starts binding again....luckily my LSD is under warranty for another 3.5 years/40,000+ miles. If it's going to start binding again, it will probably do it within a few thousand miles...and as soon as it does I am going to take it straight to the dealership.

To those of you thinking about using Mobil 1 synthetic 75w90 in your LSD, I would highly recommend against it. I know some people have had no problems with it, but when I first switched over to Mobil 1 in the LSD I had to use 2 bottles of friction modifier to get it to stop binding (it was binding really bad with only 1 bottle of friction modifier). I had zero problems with my LSD before I switched to Mobil 1 Synthetic and I know I am not the only one who has had problems with Mobil 1 synthetic in the LSD.
 
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#26 · (Edited)
Pb said:
You just needed to add more friction modifier. That binding was just the clutches in the diff.

I have Mobil 1 in mine, and no problems at all. But I will probably switch to Royal Purple or Red Line later on.
Click to expand...

I had already added 2 bottles of friction modifier to the LSD when I had Mobil 1 in there....if I needed to add another bottle it probably would have been easier to just fill the whole damn thing up with friction modifier. Even with the 2 bottles of LSD additive, the binding came back within a few thousand miles....I just don't think our LSD's like Mobil 1 synthetic. I know that you and some others have had no problems, but there are also quite a few people who have had serious problems after switching to Mobil 1.
 
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