Caution – Differential Gear Oil Equivalent

[Daless2]

Caution – Differential Gear Oil Equivalent

This week I plan to change the Differential gear oil in my FR-S as I am approaching 2,000 miles. After reading most threads on this forum as to what is the best gear oil to use I have decided to be cautious and use exactly what Toyota recommends.


In the Factory Service Manual Toyota lists two different gear oils as follows:

For NON LSD (Limited Slip Differentials) use: "LT" 75w – 85 GL-5 or equivalent

For LSD use: "LX" 75w – 85 GL-5 or equivalent


Please take note these are not the same gear oils (LT vs. LX). This leads me to believe the FR-S LSD Differential requires some type of additive in the gear oil that is not required for the Non LSD

I understand this is a TORSEN design differential which does not have a clutch pack. I have also read many times that friction modifier is not required in this type of differential because there are no clutch packs. But this raises other questions.

One:
What is in the “LX” Gear Oil that Toyota recommends for LSD that is not in the "LT" gear oil used for Non LSD differentials?

Two:
How do I know which aftermarket gear oils have the same stuff in it? (Equivalence?)


Until I can get satisfactory answers to those two basic questions I will not be using Motul, Amsoil, Redline or anything else in the differential. I will be using what Toyota recommends: "LX" 75w – 85 GL-5.

Can anyone shed any light or knowledge that might help answer these two questions? It would be appreciated.

[Chimpo]

LT
http://jaytec-lubricants.com/index.p...roducts_id=112
LX
http://jaytec-lubricants.com/index.p...roducts_id=113

Not much there after a 10 sec google search other than LT is for normal/low temps and LX helps prevent chatter.

[Hanakuso]

I wonder what both the FRS and BRZ come with from factory. Subaru or Toyota oil. I'm somewhat skeptical what to use for the diff. I was thinking of using the Motul one that is made specially for LSDs. I would like to use the Subaru stuff but I heard they only come in bulk.

[rice_classic]

Our diff, which is not a clutch/plate diff, does not need any special additive.

However some users have reported that our diff (by nature of its function) does chatter when turning sharply from a stop, like is done in every day traffic driving, and that a change in fluid has improved this.

[bluesubie]

Originally Posted by Daless2

Two:
How do I know which aftermarket gear oils have the same stuff in it? (Equivalence?)

Do a virgin oil analysis on the factory fill and then hunt for a gear oil with similar metallic additives. Still may not be the same since a uoa will not show non-metallic additives or base stocks.

Dennis

[Daless2]

Hi Folks,
I have a little more information as a result of some effort today

The NON LSD "LT" 75w – 85 GL-5 has a Toyota Part Number of 08885-02506 and cost $30.89 from my dealer per bottle.

The LSD "LX" 75w – 85 GL-5 has a Toyota Part Number of 08885-02606 and cost $43.81 from my dealer.

Clearly Toyota is saying that LSD Differentials require a different Gear oil then Non LSD Diffs.

If that is the case, and I have no reason to doubt it, I don’t think it is wise to think “Equivalent Gear Oil” can be found simply by matching the weight (75w-85) and the Grade (GL-5).

Both Toyota Gear oils have the same weight and grade.

What is different, according to the manufacturer is the Name (LT vs. LX), the part Numbers, the Cost and some unknown additive package that is in the LSD “LX” gear oil as required according to Toyota.

Not sure I am any closer to knowing what that additive package is, but I do feel more comfortable in my understanding that straight 75w-85 GL-5 gear oil is not “equivalent” to what Toyota states is a requirement for the rear diff in my LSD FR-S.

I have a call into Toyota Motor Manufacturing, Kentucky to see if they can give me more information on these two gear oils. Should I receive any feedback I will be sure to post the information here.

Also found out today these two diff gear oils are the same used in the rear wheel drive Trucks and Lexis vehicles. Non LSD uses “LT”; With LSD uses “LX” gear oil since 2009. Also found TSB to dealers to use these gear oils as replacements for all rear wheel drive vehicles going back to 2002.

Any info you might have or come across will be appreciated.

[SubieNate]

Do any of Toyota's vehicles (trucks?) come with a rear diff that does need a friction modifier (e.g., a clutch type rear diff.) I don't think the distinction they're making is specific to the FR-S, sounds like it's a general Toyota vehicle thing.

With a Torsen type rear diff, I fail to see what the big deal is in choosing an oil.

Nathan

[mkiisupra]

Originally Posted by SubieNate

Do any of Toyota's vehicles (trucks?) come with a rear diff that does need a friction modifier (e.g., a clutch type rear diff.) I don't think the distinction they're making is specific to the FR-S, sounds like it's a general Toyota vehicle thing.

With a Torsen type rear diff, I fail to see what the big deal is in choosing an oil.

Nathan

The old Celica/Supra lsd units require modifier package added, as they are the clutch type. The FR-S unit is different than them. And I really like the inside wheel 'scoot' at slow takeoff around corners from the 'tight' differential on the FR-S!


Eric G

[Daless2]

Originally Posted by SubieNate

Do any of Toyota's vehicles (trucks?) come with a rear diff that does need a friction modifier (e.g., a clutch type rear diff.) I don't think the distinction they're making is specific to the FR-S, sounds like it's a general Toyota vehicle thing.

With a Torsen type rear diff, I fail to see what the big deal is in choosing an oil.

Nathan

Hi Nathan,

Thanks for your thoughts. I don't know if the newer Toyota trucks have the clutch plates or not. I do know the old HiLux trucks did but that was in the early 90's I believe. And as Eric has mentions the old Supra MKII and MKIII also had the clutch plates that required the friction modifier.


As for the newer vehicles I do not know.


I do know Toyota in recent years has installed "Brake Centric" LSD in some vehicles. These systems work via computer control to "brake" a slipping wheel to re-direct power to the non slipping wheel. That said I do not know if they have clutch plates as well. Something worth looking into.


As for if being a big deal or a small deal as to which Gear Oil to use... That is in effect the question here.


My Owners Manual, and the Factory Service manual for my FR-S clearly states that Toyota LX 75x-85 GL-5 or equivalent gear oil should be used on a LSD FR-S.


And that my friend is what is creating the conflict with me being it is at odds with what many owners are using.


Perhaps as you suggest this is general "Toyota Verb-age" that has made it's way into the FR-S service documentation in error. But something or someone is in error here and I don't want to be the one making it. Thus this post and request for assistance.


I appreciate your thoughts and plan to investigate some more today.


I have to keep reminding myself, so as not to fall into the trap of assuming the difference between these two Toyota Gear oils is "Friction Modifier".

It is tempting to think that but in fact that is what is unknown.

Maybe it is Friction Modifier, or maybe something more exotic like Pixie Dust (LSD) that is required for the TORSEN LSD. I simply do not know but desire to find out with every one's help.


Have a great day.

[Daless2]

Good morning folks,

Yesterday I finally managed to change the differential gear oil in my FR-S.

I decided to use what Toyota recommends which is Toyota branded "LX" 75w – 85 GL-5, for Differentials WITH LSD. I am not 100% sure this is required for the Torsen design diff in the FR-S but it is the only gear oil I can find documented in all Toyota manuals and materials. It is also the only gear oil the three Toyota dealers I checked with will recommend. Take that for what you think it may be worth.

Given this gear oil is recommended, and is 100% synthetic I feel comfortable with my choice.

The only remarkable note I can make is that the magnetic plug did indeed have a significant amount of metal shavings on it. I am glad I changed the gear oil out and have clean stuff in there now.

Have a great day, I plan to!

[Hanakuso]

Originally Posted by Daless2

Good morning folks,

Yesterday I finally managed to change the differential gear oil in my FR-S.

I decided to use what Toyota recommends which is Toyota branded "LX" 75w – 85 GL-5, for Differentials WITH LSD. I am not 100% sure this is required for the Torsen design diff in the FR-S but it is the only gear oil I can find documented in all Toyota manuals and materials. It is also the only gear oil the three Toyota dealers I checked with will recommend. Take that for what you think it may be worth.

Given this gear oil is recommended, and is 100% synthetic I feel comfortable with my choice.

The only remarkable note I can make is that the magnetic plug did indeed have a significant amount of metal shavings on it. I am glad I changed the gear oil out and have clean stuff in there now.

Have a great day, I plan to!

Thanks. I am planning on doing this or possibly going the Motul LSD specific route

[ATL BRZ]

Bump from the grave. Still no definitive answer so I'll just ask. Who is currently using gear oil in their OEM Torsen diffs that have the LS Additives?

[roddy]

Most (but not all) aftermarket gear oils these days contain friction modifiers (LS additives) to help make engagement/disengagement a smoother process. I am using Redline's 75W85 GL5 in mine...details here: http://www.redlineoil.com/product.aspx?pid=40&pcid=4


It has been my experience in the past with clutch type differentials (so not really relevant to our cars) that the amount/quality of these friction modifiers isn't high enough. I've used Redline, Amsoil, Royal Purple, and others in various cars over the years, and still had to add a small bottle of friction modifier (usually about 4 ounces) to quiet the diff and eliminate chatter. Anyhoo, I digress...our differentials are Torsen, not clutch type.


With a Torsen, friction modifiers are not required, but having some in there wont hurt anything. Some people have reported less chatter when using an LS type oil in our rear ends.

[limitedblkwrx]

I use Motul PA90, over 11,000 miles no issues.