: limited slip additive



M5eater
10-19-11, 09:53 PM
So, it's 5500 miles, and before I go to MIR I want to change the rear diff fluid, I have the M1 LS oil already, and I have yet to get the 4oz of GM additive, but my question is;

is there an exact science to how much to add or is it just as-needed?

The LS oil is supposed to have some additive in it, but the M1 website states high-performance applications may need additional additive.

Thanks

thebigjimsho
10-20-11, 02:35 AM
4 oz sounds right. I would always add it.

TMC CL65
10-21-11, 09:19 AM
When are you going to MIR?

Tom

M5eater
10-21-11, 09:40 AM
When are you going to MIR?

Tom

The 757goat club rented the track for the day on the 28th, I'm tagging a long because I still have G8 friends.

TMC CL65
10-21-11, 09:51 AM
The 757goat club rented the track for the day on the 28th, I'm tagging a long because I still have G8 friends.

Cool. We also have a rental on 11/11 at MIR. you are more than welcome to come to that one too. Any mods done?

Tom

M5eater
10-21-11, 09:59 AM
Cool. We also have a rental on 11/11 at MIR. you are more than welcome to come to that one too. Any mods done?

Tom

Thanks for the offer!! I'll consider it.

Just stock, Im waiting a while longer to see if any major problems make themselves known before I start doing some warranty voiding stuff. I also need to go back to the dyno when it's not 100F and to see what sort of 1/4 times I can manage on stock power for baselines. Or at least that's the excuse I tell myself.

RippyPartsDept
10-21-11, 10:02 AM
GM's LS additive is a 4oz bottle

M5eater
10-21-11, 10:16 AM
GM's LS additive is a 4oz bottle

lol, have you had your coffee yet? Are you insinuiating I should just dump the whole bottle in, regardless if the oil I'm using already has some in there?

RippyPartsDept
10-21-11, 11:17 AM
no, i don't drink coffee ... and no

i was just kind of confirming TBJS' comment in post #2

M5eater
10-21-11, 11:42 AM
oh, ok, I knew it was a 4oz bottle, but I was under the presumption 4oz is for oil without any additive, and m1 ls states it has some, so the original question basically surrounded whether I should still dump in the whole 4oz or should I add only 1/2-3/4 of the bottle.

RippyPartsDept
10-21-11, 01:41 PM
ah, ok well i'm not really sure on that one...

thebigjimsho
10-21-11, 07:09 PM
Dump it all in. Amsoil went from not needing additive on their Severe Gear to needing it for our Vs. I dumped an entire bottle of Amsoil additive.

MrMaschine
10-21-11, 07:16 PM
Hi can someone tell me how much fluid this differential takes and what fluid is recommended from GM? does the GM stuff have a posi additive or that must be added?I want to change mine just for the sake of it since im at 23k miles it def wouldnt hurt.

M5eater
10-21-11, 07:36 PM
Hi can someone tell me how much fluid this differential takes and what fluid is recommended from GM? does the GM stuff have a posi additive or that must be added?I want to change mine just for the sake of it since im at 23k miles it def wouldnt hurt.
you will need 2 quarts, I was just able to get ~ 1.4quarts in tonight. The new Dexron LS P/N does not need the additive.


Dump it all in. Amsoil went from not needing additive on their Severe Gear to needing it for our Vs. I dumped an entire bottle of Amsoil additive.
is there some sort of link where they state that? I did some googling today and the only conclusions I've come to are;
1) mobil1 LS has additive
2) too much additive isn't a good thing either-- too much will make the clutches slip too much and they won't grab correctly. It will also have other effects such as reducing the oil's resistance to heat and oxidation.
3) some people dump the whole 4oz bottle in, but only because they've heard from other people to dump it all in, rather than any acutal quantatative evidence.

Mobil's own FAQ about this essentially just says the new Dexron LS has a specific amount and that additional amounts of LS additive will be needed, but of course.. there is no absolute quantity.

so here's a thread I found;
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2165209

basicly; put as little as you need to eliminate chattering, and no more, as the only way to do this is to simply experiment, I'll add half and dump the rest in if I need to.


edit;
and here's what I was looking for;
http://www.amsoil.com/mygarage/ProductRecommendations.aspx?FromIndex=1&url2=2011+CADILLAC+CTS+W










Engine, with filter..........6.1 quarts [1]
Cooling System, Initial Fill..........12.5 quarts
AMSOIL Antifreeze and Engine Coolant
Cooling System, Intercooler Initial Fill..........2.5 quarts
AMSOIL Antifreeze and Engine Coolant
Automatic Transmission, 6L90 Initial Fill..........6.7 quarts
Automatic Transmission, Total Fill
6 speed 6L90..........14 quarts
Manual Transmission, Tremec 6-Speed..........7.4 pints
Differential, With LSD Rear..........2.6 pints [2] -- I highlight this because only ~ this much came out, and I only got 1.4quarts back in with the car perfectly level
Differential, Standard Rear..........2.8 pints
Differential, With LSD, Oil Coo Rear..........3.2 pints [2]




[1] After refill check oil level.
[2] Add 3.4 ounce of limited slip additive GM Part no. 1052358
or equivalent with rear cover removed add 3.4 ounce
with drain plug removed add 2.4 ounce.

IE... you need to add ~ half- 3/4 of the bottle when using something like extreme gear that has LS additive in it already, and it's my opinion, that people which are able to get 2quarts in are jacking up the rear-only..which then would create an over-fill situation.

jft69z
10-22-11, 10:05 AM
Does the GM stuff have a posi additive or that must be added?I want to change mine just for the sake of it since im at 23k miles it def wouldnt hurt.

If you use the GM Dexron LS part # 88862624, it does not need the additive. I changed the fluid in my '11 Coupe early on without adding anything and it runs fine, no chatter (so far). I used this oil after reading the GM TSB 10-04-20-001 regarding "Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Diff Fluid)" and it recommends the Dex LS fluid. No need to remove the rear cover or flush the old fluid out per the TSB, just drain & refill.

I did look up the Amsoil offerings at the time and went to the site that M5Eater showed. I ended up getting in a lenghty email exchange with a couple of Amsoil engineers regarding their recommendation. I also sent them the TSB listed above (they knew nothing about it at the time). Their site apparently still does not reflect the TSB recommended oil, just the original synthetic that you have to add the LS additive. The reason I contacted them at the time was for the Corvette they listed Dexron LS and they had no Amsoil recommendation to replace the Dexron LS fluid: http://www.amsoil.com/mygarage/ProductRecommendations.aspx?FromIndex=1&url2=2011+CHEVROLET+CORVETTE+X

They were very nice and seemed genuinely interested as well as really quick with their response to the questions I asked, but in the end they didn't have a clear answer for our application, and no answer for their Corvette recommendation. So, I stuck with the GM fluid because I didn't want to dick around with a brand new car and have the dealer say I used the wrong fluid. I do the same with all my customer's vehicles too. If it calls for GM/Ford/Toyota, etc specific fluids, I tend to use them in the transfer cases, transmissions, differentials, cooling systems, etc. Yeah, sometimes it may cost a little more, but at least I can sleep at night knowing that I put the right stuff in their car and not just something that they sent from NAPA that their computers say will work.

Keep in mind that I don't road race the car and put it thru some of the things that these other guys do. They may have found that Amsoil, Mobile1 or something else works great for them, and have proven that it works for their situation, so that is something to consider also.

M5eater
10-22-11, 10:28 AM
If you use the GM Dexron LS part # 88862624, it does not need the additive. I changed the fluid in my '11 Coupe early on without adding anything and it runs fine, no chatter (so far). I used this oil after reading the GM TSB 10-04-20-001 regarding "Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Diff Fluid)" and it recommends the Dex LS fluid. No need to remove the rear cover or flush the old fluid out per the TSB, just drain & refill.

I did look up the Amsoil offerings at the time and went to the site that M5Eater showed. I ended up getting in a lenghty email exchange with a couple of Amsoil engineers regarding their recommendation. I also sent them the TSB listed above (they knew nothing about it at the time). Their site apparently still does not reflect the TSB recommended oil, just the original synthetic that you have to add the LS additive. The reason I contacted them at the time was for the Corvette they listed Dexron LS and they had no Amsoil recommendation to replace the Dexron LS fluid: http://www.amsoil.com/mygarage/ProductRecommendations.aspx?FromIndex=1&url2=2011+CHEVROLET+CORVETTE+X


They were very nice and seemed genuinely interested as well as really quick with their response to the questions I asked, but in the end they didn't have a clear answer for our application, and no answer for their Corvette recommendation. So, I stuck with the GM fluid because I didn't want to dick around with a brand new car and have the dealer say I used the wrong fluid. I do the same with all my customer's vehicles too. If it calls for GM/Ford/Toyota, etc specific fluids, I tend to use them in the transfer cases, transmissions, differentials, cooling systems, etc. Yeah, sometimes it may cost a little more, but at least I can sleep at night knowing that I put the right stuff in their car and not just something that they sent from NAPA that their computers say will work.

Keep in mind that I don't road race the car and put it thru some of the things that these other guys do. They may have found that Amsoil, Mobile1 or something else works great for them, and have proven that it works for their situation, so that is something to consider also.
It's interesting that amoils then lists exact amounts for the V2's rear but not the vettes, even though they both spec the same GM oil.

jft69z
10-22-11, 10:57 AM
It's interesting that amoils then lists exact amounts for the V2's rear but not the vettes, even though they both spec the same GM oil.

Are you talking about capacities of the diff itself, or the type of oil. On the Corvette site it does list the capacity at 4.3 pints, with the Dexron LS oil being the recommended fill (same as TSB for the CTS-V).

On the CTS-V site it says 2.6 pints, but lists the older GM oil that also needs the additive (not the Dexron LS per the TSB)

Marcuse12
10-22-11, 11:01 AM
I used Redline gear oil, which states no LS additive is needed, and put in 1/2 a bottle of the GM LS, and I'm fine 5000 miles later.

M5eater
10-22-11, 11:03 AM
Are you talking about capacities of the diff itself, or the type of oil. On the Corvette site it does list the capacity at 4.3 pints, with the Dexron LS oil being the recommended fill (same as TSB for the CTS-V).

On the CTS-V site it says 2.6 pints, but lists the older GM oil that also needs the additive (not the Dexron LS per the TSB)

exact additive amounts, maybe their cts-v reccomendations are simply not updated, but they list the sevear gear oil, and then put the quotations, where as they do not have a reccomendation at all on the vette. I wonder then if their additive reccomendation is based on the GM fluid or on their own fluid. If they're using the old fluid, you would assume the entire bottle is used.

jft69z
10-22-11, 01:23 PM
exact additive amounts, maybe their cts-v reccomendations are simply not updated, but they list the sevear gear oil, and then put the quotations, where as they do not have a reccomendation at all on the vette. I wonder then if their additive reccomendation is based on the GM fluid or on their own fluid. If they're using the old fluid, you would assume the entire bottle is used.

It looks like for the Vette, they don't recommend the additive because they spec out the Dex LS fluid which already has the additive in it. Amsoil did not have a recommendation from their product line to replace the GM fluid (Dex LS). For the CTS-V they have the old spec GM oil that needs the small bottle of additive. They were recommending their Severe Gear oil as a replacement for the regular GM synthetic fluid. That was my initial question to Amsoil at the time, how come they didn't have the updated Dex LS oil per the TSB listed. It seems they never updated it for the CTS-V. As far as amounts of additive, hmmm. If you look at the full write-up on their gear oil it says "AMSOIL Severe Gear is compatible with most limited-slip differentials. If limited-slip differential chatter occurs, add AMSOIL Slip-Lock™ friction modifier additive.

The info on the bottom of the Vette/CTS pages in regards to capacities and amounts of additive seem to be for the factory spec oils.

M5eater
10-23-11, 10:57 AM
well, I drove around yesterday and then ended with 3-4 figure 8s in the wally-world parking lot-- no noise on 1.4 quarts of Mobil 1 LS and 2.1-2.2oz of diff additive.

Also took a sample of the diff oil to send to blackstone.

thebigjimsho
10-23-11, 09:19 PM
OK, here is my real world FACTUAL experience: I replaced the diff fluid in my '09 in June '10 with 75W90 Severe Gear. I used no additive as Amsoil did not recommend it. I did a couple of track days and about 10-12k miles from June into the fall. As it got cooler(below 60), the diff would start to groan. As the temps dropped, it would groan like a sumbitch when cold. It eventually groaned all the time. At this time, C66 Racing recommended Amsoil was changing their recommendation to adding the additive in the V2.

So I got more Severe Gear and additive and it was quiet in the cold, in the heat, after track days, whatever. So I ain't pulling it out of my ass...

M5eater
10-23-11, 09:31 PM
OK, here is my real world FACTUAL experience: I replaced the diff fluid in my '09 in June '10 with 75W90 Severe Gear. I used no additive as Amsoil did not recommend it. I did a couple of track days and about 10-12k miles from June into the fall. As it got cooler(below 60), the diff would start to groan. As the temps dropped, it would groan like a sumbitch when cold. It eventually groaned all the time. At this time, C66 Racing recommended Amsoil was changing their recommendation to adding the additive in the V2.

So I got more Severe Gear and additive and it was quiet in the cold, in the heat, after track days, whatever. So I ain't pulling it out of my ass...
I'm not doubting that additive is needed, I'm doubting that you need 4oz of it. More is not better in this case, and so far, 2oz or so is working.

thebigjimsho
10-23-11, 10:06 PM
I've had no issues with a lot of driving and some track days...