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Discussion Starter · #1 ·
Hey IS owners with stock or TRD LSDs - how often should you change your gear oil?

I am running Redline 75W90 oil in my TRD LSD for about 10K now, Trac Off most of the time with minimal track use, mostly jackrabbit starts at stoplights :)
 

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stock LSD - I change mine every 15k. It had some metal particles on the drain plug on the first change (26k now so only one change so far).
 

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Shoot. I've got over 25k miles, and I don't think any of the services I've been to has replaced the oil in the LSD. How often is it supposed to be replaced ?

--k
 

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Discussion Starter · #4 ·
Maintenance manual

Hmmmm... the maintenance manual has a note under the 30K service column to change the differential oil, but only under certain conditions. I guess every 30K is a good rule of thumb.
 

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I do mine once a year along with the coolant and tranny. Definately overkill but if your a DIY'r it's cheap and it keeps stuff working optimally and is also good for peace of mine IMHO.
 

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My Lexus Master Tech does mine every 15 K for sure...... I watched him on my last two.... He highly recomended doing the tranny and rear every 15 K....

For those who have LSD.... Be sure if you change the oil independently, along with the regular Differential oil that goes in the rear end, there is an LSD additive Oil that is supposed to go in there too.... Its a very small bottle that the dealership sell, I think its like 4 0r 8 ounces... It only cost $10 bucks....
This additive is essential for the LDS rears, it adheres to the LSD components to minimize friction and eliminate noise/whine from the LSD on slow starts and inclines...
Trust me, if the oil is changed and the additive is not added for the LSD, you will here the difference... It is not harmful to the rear if its not there, but it should be added every drain and re-fill along with the regular differential gear oil...

Joe Z 8)
 

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LSD additive is only required for clutch type LSDs, like the trd unit. Stock IS300 lsd is a torsen, no additive required.
 

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krompir said:
LSD additive is only required for clutch type LSDs, like the trd unit. Stock IS300 lsd is a torsen, no additive required.
Thats great.... I have driven my car which has the stock LSD, with out the additive and with the additive.... THERE IS A DIFFERENCE....!
There is a noticebale noise/whine on inclines and slow starts which comes from the LSD, when there is NO additive.

I don't know who/what your source is, but mine is from experience on my car. Along with the help of my good friend who is a Master Tech at a Lexus Dealership...

Joe Z 8)
 

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this might be silly, but could someone post a quick DIY tutorial (ie. steps, tools required, recommended products to be used, pics would be nice too).

I have wanted to do this myself, but am afraid w/ no experience.

Thanks alot! :oops:
 

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Key word here is required. The LSD will react diffently to oil with additive vs oil without. Just because it makes noise, doesnt mean it isn't working correctly. Quite the opposite in fact. (my sources are straight from torsen, I'm sure they know a bit more about this topic than a "Lexus Master Tech")

Friction modifier is a friction reducer. It's designed to make clutch surfaces a little slipperier so that they operate smoother. As a result, the performance is reduced slightly. The same holds true with a Torsen. Adding modifier reduces the friction in the differential, with a slight negative impact on performance. Under normal driving conditions the difference is negligible. The trade off for quieter, smoother operation is considered worthwhile. Under racing conditions NVH issues aren't normally important. Then the modifier could be eliminated to achieve max performance.
Use of friction modifier is not required, and will not improve performance of the differential. However, when using non-friction modified oil, you may notice a slight "rusty screw" squeaking noise in a tight turn under light to moderate throttle. There is no harm done to the differential when this noise occurs. Friction within the differential sets up a vibration in the axle that may be heard as an audible noise. GM Friction Modifier will eliminate this noise if it becomes objectionable.
Check out this link for the full story http://www.ls1info.com/article.php?sid=141

I race my car, so performance is my upmost concern. I guess if you want a quieter ride, you can use some additive or buy an LS430 :)
 

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No trying to burst your bubble here bro.... but i guess you didn't read my last post below your first one..... No hard feelings...

Joe Z said:
My Lexus Master Tech does mine every 15 K for sure...... I watched him on my last two.... He highly recomended doing the tranny and rear every 15 K....

For those who have LSD.... Be sure if you change the oil independently, along with the regular Differential oil that goes in the rear end, there is an LSD additive Oil that is supposed to go in there too.... Its a very small bottle that the dealership sell, I think its like 4 0r 8 ounces... It only cost $10 bucks....
This additive is essential for the LDS rears, it adheres to the LSD components to minimize friction and eliminate noise/whine from the LSD on slow starts and inclines...
Trust me, if the oil is changed and the additive is not added for the LSD, you will hear the difference... It is not harmful to the rear if its not there, but it should be added every drain and re-fill along with the regular differential gear oil...
Basically, all I was saying is that if you have LSD and don't want any noise from it use the LSD additive oil... Of course most of us use our cars "Under Normal Driving Conditions"..
No where in my post did I say "Just because it makes noise, doesnt mean it isn't working correctly!!!!" :noway:

BTW - I sold my race car when I bought my IS, so performance is still my upmost concern... However, if I wanted a noisy rear I would have kept my 3.73 MotorSport with Posi Traction...

Thanks
Joe Z :D




krompir said:
Key word here is required. The LSD will react diffently to oil with additive vs oil without. Just because it makes noise, doesnt mean it isn't working correctly. Quite the opposite in fact. (my sources are straight from torsen, I'm sure they know a bit more about this topic than a "Lexus Master Tech")

Friction modifier is a friction reducer. It's designed to make clutch surfaces a little slipperier so that they operate smoother. As a result, the performance is reduced slightly. The same holds true with a Torsen. Adding modifier reduces the friction in the differential, with a slight negative impact on performance. Under normal driving conditions the difference is negligible. The trade off for quieter, smoother operation is considered worthwhile. Under racing conditions NVH issues aren't normally important. Then the modifier could be eliminated to achieve max performance.
Use of friction modifier is not required, and will not improve performance of the differential. However, when using non-friction modified oil, you may notice a slight "rusty screw" squeaking noise in a tight turn under light to moderate throttle. There is no harm done to the differential when this noise occurs. Friction within the differential sets up a vibration in the axle that may be heard as an audible noise. GM Friction Modifier will eliminate this noise if it becomes objectionable.
Check out this link for the full story http://www.ls1info.com/article.php?sid=141

I race my car, so performance is my upmost concern. I guess if you want a quieter ride, you can use some additive or buy an LS430 :)
 

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I changed mine with mobile one without any additives about 10k ago and have not have any problems or noises. I'm just going by what my Lexus delaer told me and did not add any thing. I'm not saying it's wrong to add anything, but it may not be necessary. JoeZ, would it be safe to say if there are no noises then the additives are not required, and to only add it if you got noise issues?

As far as changing the oil, it's really easy, since we got a drain plug. First thing to do is remove the fill plug, if I remember correctly, it's on the passengers side top. Take this off first, cause if you drain the diff and can't get the fill plug off, you're screwed. Then remove the drain plug and let it drain all out. replace plug and fill to bottom of threads in the fill plug. It's really helpful if you get one of those hand pumps to fill the diff. You wll need a allen socket or wrench (I think it was 10 or 12mm) for the plug. It's really simple, more easy then changing the engine oil. Try to drive the car for a few blocks to get the fluid warmed up so it flows easier.
 
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