I just stopped by my dealer to check the price for replacing the my rear diff lube with the GM specified lube. During my conversation with the service personnel I found out some information I thought was very interesting.

The first and probably the most troubling was the price/quart for the grape juice at $16.00. At first glance this seems to be in line with everyone elses reports, now comes the troubling part. My wifes aunt lives in Canada so I had her check on the price for grape juice in Canada. The price she was quoted is $6.00/liter with exchange that is approxiamtely $4.50/literhttp://www.dieselplace.com/forum/smileys/Ermm.gif.
Just a point of referenced a one liter equals approximately 1.0566882 quarts. How can this be?http://www.dieselplace.com/forum/smileys/Confused.gif?

Second, which I found the most interesting, is my dealer does not replace grape juice with grape juice. They buy Mobil 1 Synthetic in bulk and use that for replacing the GM original gear lube. Does this seem logical?

They didn't quote her the proper price. They most likely quoted her on a substitute gear oil and not the GM grape juice. I have priced out the GM Grape juice and it is more expensive here then it is in the US. This is the case with most, if not all GM parts.


Lots of people substitute Grape juice for a good quality synthetic hear oil such as Mobil 1. If GM wasn't so greedy they would sell a lot more product. I would consider paying more for GM parts, maybe even double, but 4 times the cost is outrageous.

If you can get it for $16 per quart, thats a good deal. Keep in mind that its a one time change (per GM). Considering I spent almost $35k for the truck, I spent the money and bought the grape juice. Its the only lube that meets GM's spec. I'm not saying its the only lube that will work, just the one that meets their spec.

Why waste your money on it? I've been building transmissions and setting up gears since I've first turned a wrench. I've seen more problems because of synthetic rather than good stuff from it. Put regular 80/90 in it and it will last a long long time. If its a posi unit throw some of the GM or Ford friction modifier additve in it. Oh yea, A quart of 80/90 is about a $1.25 .http://www.dieselplace.com/forum/smileys/Confused.gif

Why waste your money on it? I've been building transmissions and setting up gears since I've first turned a wrench. I've seen more problems because of synthetic rather than good stuff from it. Put regular 80/90 in it and it will last a long long time. If its a posi unit throw some of the GM or Ford friction modifier additve in it. Oh yea, A quart of 80/90 is about a $1.25 .<IMG style="WIDTH: 25px; HEIGHT: 23px" height=36 src="smileys/Confused.gif" width=39>

Well I have not seen any problems from synthetic gearoil use but I have not seen any real gains either other than in extremely cold climates. Also GM does not make the "Grape Juice" themselves and soonner or later it should be availible through a third party or the manufacturer of it themselves. I think the "spec" hipe is to get you to keep buying the oil from GM, not because existing gear oils will not work just fine.

GM advises against using a friction modifier in the Eaton unit. Also, it specs out SYNTHETIC lube in the axle. Could lead to warranty issues

GM advises against using a friction modifier in the Eaton unit. Also, it specs out SYNTHETIC lube in the axle. Could lead to warranty issues

This is true on warranty issues but I doubt if they will do a oil anylisis to see if it is synthetic. They may check to see if it was changed regularly as required by service type though. I still think frequent changes with "dino" gear oil is better than infrequent ones with synthetic because there is no "filter" in the axle assembly to remove grit or dirt as it develops with use and time.

agree with that, but when your limited slip starts acting up....


thats alot of money for that unit, and even old worn out grape juice is still identifiable by smell... Why chance it? TMO.

agree with that, but when your limited slip starts acting up....


thats alot of money for that unit, and even old worn out grape juice is still identifiable by smell... Why chance it? TMO.

It would be interesting the read the GM "spec" because gearl oil is basically gear oil, the only thing that differs is its base stock or additives.

I have tried finding out what it is, but the only thing I can ever find is a part number looking thing...

I have tried finding out what it is, but the only thing I can ever find is a part number looking thing...

and what numbers are there on it or what is the GM spec number?

<TABLE width="100%" border=1>
<T>
<TR>
<TD vAlign=center align=middle>


Rear Drive Axle, All Except 9.75" Axle</TD>
<TD vAlign=center align=middle>


Lubricant</TD>
<TD vAlign=center align=middle>


12378261 (Canadian P/N 10953455) or equivalent meeting GM Specification 9986115</TD></TR></T></TABLE>

Be doing some digging and it appears than Pennzoil might make it (Grape Juice) and it is what Pennzoil calls "syncromesh fluid". It is rated at 80w and has no GL rating attached to it that I can find yet.

Here is a link to a PDF file that tell the test proceedures for the various ratings.

www.swri.edu/4org/d08/Abstracts/gearoils.pdf (http://www.swri.edu/4org/d08/Abstracts/gearoils.pdf )Edited by: snoman

I stopped at my local bulk oil and lube distributer a couple weeks ago, inquiring about the cost of buying my oil in 55gal drums verses buying by the gallon at Wally World, any how I asked him about Gear Lube and if he could recommend a good brand for a new GM, and he told me that all GM truck now come from the factory with Mobile 1 Synthetic gear lube installed in them, can anyone verify if this is correct.

Funny thing talking about the cost of grape juice. I took my previous truck to the dealer to change the "grape juice" after a plowing season. Drove it home and noticed on the service record that it was replaced with regular gear oil. I kinda noticed that it was kinda cheap for the diff service, being the bill was about 80.00 bucks. Went back and told them of the problem about the wrong fluid being put in and they took care of it right away by putting the "grape juice" back in at no charge.(Great dealer) Funny thing is that the old fluid that they drained out turned out to be grape juice after all. They documented it wrong. Turned out to be an expensive rear end service for them.

buckeye, thats BS


GM is using the grape juice in most everything

I found out a little more about synchromesh fluid (grape juice) Both Quakerstate and Pennzoil make it. On thing the GM spec does want in low sulpher gearoil (synchromesh fliud is low sulpher) and it also means that you want to use GL5 rated gear oil (which is low sulpher too) not GL4 rated oil. Below is a link to more info on Pennzoils product

Click here to find out more about Pennzoil synchromesh fliud (http://www.pennzoil.com/products/gear_oil/syncro_fluid.html)Edited by: snoman

syncromesh is for manual trans vehicles, GM has a syncromesh fluid as well

syncromesh is for manual trans vehicles, GM has a syncromesh fluid as well

GM does not make the fluid. I appears that Pennzoil or Quakerstate does for them. Also Penzoil and Quakerstate seem to have same parent company now. Edited by: snoman

I will have to go start sniffing bottles at autozone. I wonder if somebody uses the same stuff repackeged?

I will have to go start sniffing bottles at autozone. I wonder if somebody uses the same stuff repackeged?


I would start looking for bottled Pennzoil Synchromesh fluid too.

I though this was beaten in the ground years ago and someone found out it was made by Texaco? http://www.dieselplace.com/forum/smileys/Confused.gif

now that you mention it, Texeco does ring a bellhttp://www.dieselplace.com/forum/smileys/Confused.gif

Buckeye. Schaeffer's 741 100% Pao Synthetic 75-90 Eaton approved.


$1201.20 Delivered. That is about$5.45 per quart.

I though this was beaten in the ground years ago and someone found out it was made by Texaco? http://www.dieselplace.com/forum/smileys/Confused.gif

Possibly, but Pennzoil does in fact make a Syncromesh 80w fluid for GM uses.

snoman wrote"because gear oil is basically gear oil, the only thing that differs is its base stock or additives. "


uh?

Basicly I think he is saying oil is oil, its all the same, the only thing that differes is the base stock and its additive package. Just some minor differences since all any oil is just its base with its additive package.....it all makes sense to me lol http://www.dieselplace.com/forum/smileys/Wacko.gif

Basicly I think he is saying oil is oil, its all the same, the only thing that differes is the base stock and its additive package. Just some minor differences since all any oil is just its base with its additive package.....it all makes sense to me lol http://www.dieselplace.com/forum/smileys/Wacko.gif

Yes, by base stock I mean weather it is off of synthetic or crude (and the different types of crude too) It is the additives to it that make it GL3, GL4 or GL5 and so on as well as the "weight" of it and when it is multivis (like 85w-140) they also add VI improvers to stabilize oil viscoscity (though VI's themselves add nothing to the oils lubrication qualities and actually take a tiny bit away, its a trade off)

snoman writes"It is the additives to it that make it GL3, GL4 or GL5 and so on ". This could not be further from the truth. Api group I and II base oils roughly double CCS(cold cranking simulator) viscosiity fo r every 5 degree C drop. Group III and IV incresa viscosity even further.


All oils superiority or lack there of is dependent on The quality of the base stock, its add pkg. and its blending process. Base oils compromise about 80% of the total pkg. THIS is important.

Buckeye. Schaeffer's 741 100% Pao Synthetic 75-90 Eaton approved.


$1201.20 Delivered. That is about$5.45 per quart.





"Eaton Approved" and Schaeffer's to boot. That's why it is in both my front and rear diffs.


I think you meant $120.00 not $1201.20. The price looks high because the smallest container is 5 gallon buckets.Edited by: HOOKEM

I thought the buckeye said 55 gal. 5 gal is about 120 wholesale.


sooooooooooo hook em how does it feels








Please check out specials on the vendor forum. Thanks.

snoman writes"It is the additives to it that make it GL3, GL4 or GL5 and so on ". This could not be further from the truth. Api group I and II base oils roughly double CCS(cold cranking simulator) viscosiity fo r every 5 degree C drop. Group III and IV incresa viscosity even further.


All oils superiority or lack there of is dependent on The quality of the base stock, its add pkg. and its blending process. Base oils compromise about 80% of the total pkg. THIS is important.

THere is the viscosity and additives. The additive determine the GL rating and the viscosity is not directly linked to GL rating. A oil can be 80w90 and be GL3, GL4 or GL5 rated depending on additives. ALso bnase oil make up more than 80% when you are dealing with "dino" oil. The additives are a very small percentage and the VI itself is less than 2% usually. Long ago there used to be the aurguement that some oils were parifin based and some were not (pennslvinia crude) but they all come for basically the same crude now if they are dino oil and most synthetic are based on hydrocarbons for compatabilty with existing oils. There was a time when some synthetics were ester based and did not get along with regular oil at all. (aircraft turbine oil is mostly ester based still) There are differences in the molocue chains with a few different synthetics but basically a synthetic oil usually has a longer, thinner chain than convential oil so that it flows other itself better and resists displacement a bit better too but conventional oils have come a long way to in the last 20 years and the performance cap between them and synthetic, be it gear oil or engine oil, is not as great as it once was. Synthetic still has the edge in high temps though but that is kinda a mixed blessing because if you oil gets up to 280 or more regularly, you need to cool it better anyway.

Snoman"There are differences in the molocue chains with a few different synthetics but basically a synthetic oil usually has a longer, thinner chain than convential oil so that it flows other itself better and resists displacement a bit better too but conventional oils have come a long way to in the last 20 years and the performance gap between them and synthetic, be it gear oil or engine oil, is not as great as it once was. Synthetic still has the edge in high temps "


Low temps and thermal stability as well.


Well said. Which is why a good blend of hydrofinishished dino, high quailty synthetics blended with the a superior additive pkg is a very economical alternative to straight syn and many times a better product as well.

Snoman"There are differences in the molocue chains with a few different synthetics but basically a synthetic oil usually has a longer, thinner chain than convential oil so that it flows other itself better and resists displacement a bit better too but conventional oils have come a long way to in the last 20 years and the performance gap between them and synthetic, be it gear oil or engine oil, is not as great as it once was. Synthetic still has the edge in high temps "

I believe I just said that. I agree would have been easier. Yes, synthetics do tend to have better low temp performance (I have been using them for over 20 years in some applications so I do have some expericain with them. I live in Montana for a spell in the mid 90's where minus 40 was common and I did use synthetics while there and it did perform well in cold weather) I agree that the blended oils are a cost effective option over pure synthetic. To many people waste their money with full synthetic when it is not cost effective for their uses and the semi would make more sense. The regilar motol oil availble today is a LOT better than it was 20 years ago and motors are going a lot further today because of it too. This all started on gear oil though and I have not seen it really outperform dino oil in wear protection in a drive axle when the axle with dyno oil is properly serviced for its duty cycle and climate. Additives in gear oil are a lot more important than the base stock.

That makes sense. What do you look for in an add pkg? Or test results?

AAM builds the very heavy duty 11 1/2" in my Duramax. They said that due the tight tolerances and the heavy loads to use a GL-5 gear oil. This is absolutely the number one place on our truck that should have the superior qualities of a synthetic lube. (lower pour point, higher flash point, higher shear strength etc. etc.) Any synthetic that does not permit excessive chatter when the Eaton locks will work. I have noticed a little chatter with Mobil 1 but Eaton says that will not do any harm. I doubt that the Eaton would even work at 20 below with 90 weight dino oil. Later! Frank

AAM builds the very heavy duty 11 1/2" in my Duramax. They said that due the tight tolerances and the heavy loads to use a GL-5 gear oil. This is absolutely the number one place on our truck that should have the superior qualities of a synthetic lube. (lower pour point, higher flash point, higher shear strength etc. etc.) Any synthetic that does not permit excessive chatter when the Eaton locks will work. I have noticed a little chatter with Mobil 1 but Eaton says that will not do any harm. I doubt that the Eaton would even work at 20 below with 90 weight dino oil. Later! Frank

An oil does not have to be synthetic to be GL5.(and the difference between GL4 and GL5 is the sulpher/phosphurus compounding not the base stock) Also you can hardly get straight 90 anymore as it is either 80w90 or 75w90 dino oil. Also there is a LOT of hype about the need for synthetic oil in diffs these day. They are doing a good job convincing some people that they MUST have it in there diffs. All you really need is the correct GL rated Dino oil and the weight for the climate, anything more is questionable. Regualar changing and servicing of your diffs lube is far more important than whether it has synthetic or not.

On a side note, here is a link about the pour points of various engine oils.

Oil pour point link (http://www.vtr.org/maintain/oil-overview.html)Edited by: snoman