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new gen 4 diff, which oil? also broken out of the box ugh

8K views 70 replies 19 participants last post by  bneal1022 
#1 ·
hi guys..
very excited I made enough $ buying, refurb, and selling V parts and more to buy my own new gen 4 diff as mine is dying (those at v-day4 know) :thumbsup:. Got it home from GM dealer, they loaded it in my wifes car. I lifed it out of box and..... tink a tink tink. aluminum pieces on the garage floor. The fins in the case are all broken. Apparently it was dropped before I got it. :want::suspect::mad:

Needless to say I held the check until they get a new one for me.. I will fight that battle tomorrow.

So, I (will) have a new gen 4 diff for $1498. I know the factory oil is Mobil 75W-90 with the GM friction additive. I replaced my original diff oil with Royal Purple 75W-90 Max-Gear which already has the additive in it a year ago. It did quiet my diff for about 6 months.

So with a new new diff, what oil does the group reccommend? I was planning on just starting out with RP. thoughts?

I will be transferring my CS gray bushing... oh BTW, the new diff does not include a vent... anything I need to know about a vent? I saw posts about a vent or vent leaking issue in the past. input? :confused:
 
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#2 ·
The GM fluid is not Mobil1 75w-90. The GM fluid, Part #89021677, is the only commercially available fluid that meets GM specification 9986115, which requires a specific high temperature endurance test not required to meet the API-GL-5 standard. Technically, the use of other fluids would not maintain the original warranty. For obvious reasons, the warranty issue is moot and was never enforced because even when a differential failed the dealer had no practical way (or incentive) to tell what fluid was being used in the failed unit.

I personally still use the GM fluid because I am stubborn, but it is expensive.

If I were to switch fluids it would be to Amsoil Severe Gear.
 
#9 ·
I'm using Amsoil. Can't say it's any better or worse than anything else.
Of all fluids put in this car, a quality fluid anywhere is fine. But for the diff, I'd look for any little benefit I can. I didn't get Amsoil Severe Gear in my '04 before my accident. But I used it in my '09.

Now, is it any better? Not sure. But some guys have gotten diff temp warnings on the track. At Summit Point, I did not and you remember how oppressive it was that day? No issues. So I'm inclined to keep using it...
 
#5 · (Edited)
it depends on what you call a "gen" or part number. there have been at least 4 different part numbers for our diff. I actually have a 1308 in my car and according to several others, these never made it far in the field.

Gen. 1st---- 10361308
2nd---- 12378261
3rd----- 15793756
4th----- 25873498

Ok so that is 2 votes for the amsoil, zero for RP, and 1 for OEM. I just wanna do whats right for my new diff right out of the gate.

darkman...
is this the fluid? it is a 75w-90 synthetic. does this need the additive or not?
http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=21329

or i guess i could use the amsoil.

the RP meets API GL-5
http://www.royalpurple.com/gear-oil.html
 
#46 · (Edited)
That's what I thought (from reading this forum), but they said that they checked and it was not required to be put into the new diffs.

Is there a new GM fluid? PN? Someone earlier posted GM fluid, Part #89021677. That's the # on my invoice. They seem to think that this fluid works fine in the gen 4 diff.

Is there an 800 number Cadillac? ...because I want a 100% answer.

http://www.cadillac.com/pages/mds/helpcenter/contactUs.do ?

I'll be calling on Monday.
 
#12 ·
alright.. which amsoil weight and with w/o GM additive?

ewill
from the dealer exactly what part numbers do I need? fluid and additive? It even requires additive with 89021677
 
#13 ·
The friction modifier is the same part number we have used for years and years.
From the CTS-V owner's manual you need:

SAE 75W-90 Synthetic Axle Lubricant (GM Part No. U.S. 12378261, in Canada 10953455) meeting GM Specification 9986115. With a complete drain and refill add 4 ounces (118 ml) of Limited-Slip Axle Lubricant Additive (GM Part No. U.S. 1052358, in Canada 992694) where required. See Rear Axle
I think the 8261 number changes to the 1677 in the catalog and they just never updated the manual. ;)
The issue is most Cadillac dealers aren't used to the limited slip differential and they really don't understand that the V has one and that it requires the additive even though it doesn't have the G80 RPO on the build sheet. It has a G80 diff, but it is part of the V package and not listed as an option on the label because of that.
 
#14 ·
I use Redline and love it. I even stepped up to half 75w90 and half 75w140 and it quieted down the whine substansially. Plus it has LSD modifier built in.

I have tried the GM stuff, and it was noisy off the get go, didn't smell like grapes (lol), and was more expensive after buying the LSD modifier bottle. Booooo all around.

If you have to add LSD modifier, always put it in first. THEN, put the gear oil in. That way you make sure you get the entire bottle of modifier in there.

As far as the vent goes.... Use a socket that just fits over the vent but touches the ridge of it, and tap it into the diff with a hammer.
 
#16 ·
max - I PM you

wow, surprised to see the variety (lets call it variation) in fluids used. In the quality world variation is the enemy :hide:

still stumped on which weight amsoil? 75w-90?

my original did quiet a little with the RP, but i see nobody else using it. That should be a hint I guess. Like most, just want the BEST fluid for the diff right out the gate is a brand new unit. I may track once a year.
 
G
#20 ·
Hmmmmmmmm.





















LOL.

I have the 75W110 Severe Gear in there now and it's a little quieter. Mine screams like a pig at 45-50 mph with the GM stuff, I can hear it loud and clear over the B&B exhaust. I'm moving up to the 75W140 next time.
 
#21 ·
It seems to me that one possible contributing factor to the gear whine is wear and tear on the ring and pinion gears when cold. I say this because the differential lubrication system has no "oil pressure" and relies solely on splash lubrication. So, if you start running the car hard before the differential gets up to its operating temperature wear could be accelerated as compared with operation once it is warmed up. I use the transmission temp gauge as an indicator that the drive line is warmed up because it takes much longer than bringing the motor up to operating temperature.

The point of all this is that if you choose to go with higher viscosity fluids, I would advise even more warm up time before engaging in hard acceleration.

Of course this is just a theory.
 
#23 ·
#25 ·
so you would use the "light" shockproof which is like a 75w140 over the 75w140 gear oil? whats the difference? betweent he shockproof and the gear oil? would you still use additive? why so thick? should it not be 75w90? why have you not put into V?

i'm about to close my eyes and point at a fluid.... just want a chatter & whine free new diff with proper protection for 2 day/week driving in PA with 1 track day a year.
 
#26 ·
what about the Redline lightweight shockproof gear lube + additive? It is designed for splash lube as our diffs are, and has a heavier weight (as i see many above 75w90 into the 140 range). will still get additive to add as required... thoughts?

http://www.redlineoil.com/product.aspx?pid=43&pcid=8
 
#28 ·
Unlikely you find a a used GEN 4 for cheap, so it's probably dealership which will take you to cleaners. Now the 157 part number diffs are all over Ebay for cheap, but remember if it ain't 3.73 gearing it's not from the CTS-V, there are cheap 157, but with different gearing. When you find the 3.73 diffs they range from $800-1000, the odd few slip through the cracks on ebay for $550-650 price range.

I have a updated GEN 3 and axles collecting dust in my shop if anybody needs one.
 
#29 ·
junk yards around the us, cleveland pick a park and ebay always have 157*** 3.73 limited slip V diffs for cheap (~$500, seen a few for even less).

Im running a gen 1 diff, And id like to one day upgrade but im tryin to decide whether to upgrade to the 157**** or just keep saving and buy a new gen 4
 
#30 ·
max.. the part numbers i gave earlier are all 3.73 the key to the final diff solution is the robust prop shaft boss on the front of the diff. The case of the gen 4 is meatier and better structurally. I can't explain the "diff" between the diffs (get it, diff joke), until the latest. If interested I can likey get you the same offer for a new gen 4 i got on mine. Just talked about it with my friend at the parts counter last night. PM me if interested.

I woudl reccommend just finding a way to go for it all and get a 4th gen. I will be installing it with my newer Gforce passenger side econo axle and DMH cutouts...

i think I will use the redline lightweight shockproof gear oil with 1oz of additive as needed. unless others object (i'm listenting)
http://www.redlineoil.com/product.aspx?pid=43&pcid=8
 
#32 ·
how about a break in period? How long (in miles) should i go with new fluid and 4oz additive to reduce temps for break in, then change out to fresh fluid and additive only as needed? should i use a different weight oil during break in? should i take a long run for a while or short regular use for break in?
 
#33 ·
how about a break in period? How long (in miles) should i go with new fluid and 4oz additive to reduce temps for break in, then change out to fresh fluid and additive only as needed? should i use a different weight oil during break in? should i take a long run for a while or short regular use for break in?
The break-in procedure that I used at the recomendation of a Service Manager was as follows:

For the first 500 miles-
1. Avoid constant differential rpm - that is don't go on a long trip on the interstate and try to vary speeds as much as traffic allows.
2. Heat cycling - Avoid driving more than 30 minutes without a cool off period.
3. Avoid full throttle unless you are about to let it cool down for awhile.
4. Change the fluid at or about 500 miles.
 
#34 ·
thanks darkman !! the info below is from redline's page about diff break in. sounds like i will use 75w90 or stepped to 75w140 with the additive as specified below with your notes above.. thoughts?



MORE TECHNICAL INFORMATION


Limited-slip or Positraction units use plates or clutches to provide the proper amount of lock-up to the differential. Slippery lubricants are required to prevent chatter, but too much slipperiness causes excess wheel spin, reducing traction.
For perfect traction, use Red Line 75W90NS and add the Red Line Limited-Slip Differential Friction-Modifier / Break-In Additive until the chatter disappears.

Satisfies performance requirements of GM 1052358, Ford M2C118-A, 19B546-MA, Chrysler 4318060 and most imports.

Recommended Dosage:
Use 4% for prevention of limited slip chatter in broken-in units (typical one 4 oz. bottle) or 4 to 8% for the break-in of new differentials.

Red Line Limited-Slip Differential Friction-Modifier / Break-In Additive will significantly reduce the friction during break-in of differentials. High temperatures encountered in break-in
can destroy the hardening of the gear teeth causing rapid wear of the softened gears. This additive can reduce the break-in temperatures by as much as 50°F, improving break-in conditions. Compatible with petroleum or synthetic gear oils. Red Line Gear Oils already contain this additive (except the NS).

In non limited-slip racing differentials and quick change units using the Red Line ShockProof Gear Oils an additional 3 to 6% Red Line Limited-Slip Differential Friction-Modifier / Break-In Additive is recommended.
 
#36 ·
Tangential post here:

Dropped the V off at Lindsay on Monday to replace leaky water pump & asked Alex (service writer) to see if my warranty provider would cover a diff replacement. Total wildcard request... I have the standard 45-65mph whine, but that's it. Frankly, I wasn't sure how extensive my driveline coverage was and at the least the request would let me know.

I had asked Bill (senior tech) there to evaluate my diff when I took it in for the VDay IV check-up early in June and he wrote up that it indeed had the whine that was likely caused by the diff housing deformation and the the std fix by Cadillac is full diff replacement.

Yesterday the warranty provider sent out an inspector, Bill gave him the 'let me tell you 'bout CTS-V diff' speech and, for the cost of my $250 deductible for a water pump replacement, I'm getting $3k+ parts and labor that includes a new current generation differential. They guy didn't even drive the car!

I feel like I just got a hole in one. I'd be buying you all drinks right now if you were in the area!

I heart Bill and Lindsay Cadillac!

Quadruple smily icons to follow:


:ride::banana::dance::banana:
 
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