# rear diff oil change this weekend.........



## pctek (Jul 18, 2010)

This weekend I want to drain and refill my 05 goat a4 diff with torco and type f friction modifier. Can anyone point me with steps in doing so and what weight torco do i put in to help quite down the slight whining from 40 to 50 mph's and slight clunking once and a while.


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## jpalamar (Jul 22, 2008)

Owners manual says 75-140. Drain, fill until it oozes out the fill hole(should be about 1.7 quarts if I remember right). Add FM.

It is a very easy service, just make sure you have either a huge adjustabel wrench or socket. One of the bolts is massive.


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## svede1212 (Nov 1, 2005)

The Torco RGO 85-140 is the one you want


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## pctek (Jul 18, 2010)

svede1212 said:


> The Torco RGO 85-140 is the one you want


Is 85 140 vs 75 140 more thicker creating more drag resitance in the movement of the diff?


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## Poncho Dan (Jun 30, 2009)

Whatever you do, DO NOT use their SGO. People eventually grenade their diffs with that stuff. RGO only.

I need to get off my dead butt and order some, I don't think it's ever been changed...


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## GM4life (Mar 18, 2007)

Poncho Dan said:


> Whatever you do, DO NOT use their SGO. People eventually grenade their diffs with that stuff. RGO only.


Where did you hear this at?

I've been using SGO 75-140 in my diff for thousands of miles, DD, track ect. Never had problems out of it.


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## ROBSGTO (Jul 6, 2008)

GM4life said:


> Where did you hear this at?
> 
> I've been using SGO 75-140 in my diff for thousands of miles, DD, track ect. Never had problems out of it.


You may be the first person I've read to use the SGO instead of the RGO.I think the SGO(synthetic) is actually the one for GM vehicles and the RGO is for FORD.

However the RGO is supposed to be better for our cone type differentials.

I've had my Torco RGO sitting here for quite a few months,just haven't gotten around to putting it in yet.


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## GM4life (Mar 18, 2007)

ROBSGTO said:


> You may be the first person I've read to use the SGO instead of the RGO.I think the SGO(synthetic) is actually the one for GM vehicles and the RGO is for FORD.
> 
> However the RGO is supposed to be better for our cone type differentials.
> 
> I've had my Torco RGO sitting here for quite a few months,just haven't gotten around to putting it in yet.


You shure you are not thinking about the Type F/G friction modifier? The manual calls for synthetic gear oil I've heard that the manufacture(Dana) calls for regular gear oil.

I would rather use the RGO fluid I have both in my garage the RGO 85-140 and the SGO. The RGO is way thicker than the SGO 75-140. I'll take the extra drag on the gears for more cushion.


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## ROBSGTO (Jul 6, 2008)

GM4life said:


> You shure you are not thinking about the Type F/G friction modifier? The manual calls for synthetic gear oil I've heard that the manufacture(Dana) calls for regular gear oil.
> 
> I would rather use the RGO fluid I have both in my garage the RGO 85-140 and the SGO. The RGO is way thicker than the SGO 75-140. I'll take the extra drag on the gears for more cushion.


Type F friction modifier is what to use,but also the RGO is used by everyone from what I've read and what I'll be using.


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## GM4life (Mar 18, 2007)

ROBSGTO said:


> Type F friction modifier is what to use,but also the RGO is used by everyone from what I've read and what I'll be using.


I have the type F in mine. I'm just trying to figure out the SGO/RGO thing. I have no problems with the SGO.


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## Poncho Dan (Jun 30, 2009)

GM4life said:


> Where did you hear this at?
> 
> I've been using SGO 75-140 in my diff for thousands of miles, DD, track ect. Never had problems out of it.


It seemed to be the consensus on LS1. There were a few stories of people running SGO and having the clutches to hell after a while, chatter, lash, all that good stuff. They didn't necessarily "grenade". Who knows though, plenty of idiots over there, it wouldn't surprise me if they used the wrong whale sperm (or none at all).

RGO seems like the tried and true fluid though, you really can't go wrong.


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## GM4life (Mar 18, 2007)

Poncho Dan said:


> It seemed to be the consensus on LS1. There were a few stories of people running SGO and having the clutches to hell after a while, chatter, lash, all that good stuff. They didn't necessarily "grenade". Who knows though, plenty of idiots over there, it wouldn't surprise me if they used the wrong whale sperm (or none at all).
> 
> RGO seems like the tried and true fluid though, you really can't go wrong.


Ahhh got ya. SO to me it sounds like the ole stay away from Fram because someone blew their motor thing. With no hard truth.Then people jump on the bandwagon. These diffs are touchy, I had better luck with Torco than I did with anyother gear oil I've tried.

I have noting against RGO I didn't find out about it until 6QTS11OZ brought it by the house and I already had SGO ordered. I couldn't even pump the RGO out of the bottle with my hand pump thats how thick it is. It seems to work fine in his car, but I'm not going to rush to change it out because its been good to me for all these miles.


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## lowpro192000 (Jun 2, 2011)

*?*

It might be a dumb question but whats the difference between the type g and type f? I looked on the torco website and it said to use type g with gm vehicles and type f with ford vehicles. I was just wondering because i saw were people were saying to use type f on our cars?


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## svede1212 (Nov 1, 2005)

That's true about the "F" and "G" being generally for Ford and GM _BUT_ the diff is made by Dana in Australia and they designed it for Ford modifier. Even GM uses type "F" with the fluid for this car


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## TxSoldier6.0 (Nov 4, 2008)

GM now sells an all in one fluid I can't find the part number but the old fluid and friction modifier have been discontinued also the new fluid is a bit thicker your going to get a million opinions as I did but I've been running the new GM oil in my rearend for about 3 months and no issues so far save yourself the headache and get the new oil from GM


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## 87GN06GTO07IRL (Aug 10, 2009)

^^^the new fluid is actually thinner. I love it!


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## TxSoldier6.0 (Nov 4, 2008)

87GN06GTO07IRL said:


> ^^^the new fluid is actually thinner. I love it!


My bad lol I meant thinner thanks for the correction


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## pctek (Jul 18, 2010)

Now wahts the advantages/disadvantages with thinner and thicker gear oils?

I notice the oem weight of 75w-140 is thinner than the 85w-140 of the torco, so wouldnt the thicker oil cause more drag resitance for the moving diff parts?


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## 87GN06GTO07IRL (Aug 10, 2009)

pctek said:


> Now wahts the advantages/disadvantages with thinner and thicker gear oils?


Thinner protects better cold. Some say thicker gives more cushion but that's a bunch of crap if it's to thick to get where it needs to. The thinner fluid solved all of my noise issues.


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## Poncho Dan (Jun 30, 2009)

If you're only driving it in summer, nobody's going to notice the difference in the base viscosity.


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