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god of the sea people
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229 Posts
Discussion Starter #1
ok, i got a new pinion seal from my dealer, and it's still in the shop as they are waiting for a new kind of diff oil.. the writer said that the 80w90 syn is no good for these rear ends anymore, and a new oil is to be used. only trouble is, he didn't know what weight the oil was, or syn/dino... anybody know anything more about this? the writer said the tsb 'just came out' like yesterday, he made it sound.. btw it's for diff noise. i think the word he used was 'whine'.... so free diff fluid change, anyone?
 

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= Ol Dirty Ed
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3,280 Posts
Man if thats true thats great news I was just about to buy some new diff fluid and get it changed. i'll take the free change thank you off to my local quality dealer. Great post
 

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Administrator
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9,486 Posts
80W90 was never the recommended oil for the rear, if you look in your owners manual it specifies 75W140 synthetic plus GM friction modifier.
If that dealer has been putting 80W90 in them then they need to read the manual themselves.
 

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676 Posts
whatsaholden said:
ok, i got a new pinion seal from my dealer, and it's still in the shop as they are waiting for a new kind of diff oil.. the writer said that the 80w90 syn is no good for these rear ends anymore, and a new oil is to be used. only trouble is, he didn't know what weight the oil was, or syn/dino... anybody know anything more about this? the writer said the tsb 'just came out' like yesterday, he made it sound.. btw it's for diff noise. i think the word he used was 'whine'.... so free diff fluid change, anyone?
I thought we were supposed to be using a different weight like 85-140 or something like that?
 

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god of the sea people
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229 Posts
Discussion Starter #5
im just the messenger. you want free diff service or not?????
 

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Fox Mulder said:
80W90 was never the recommended oil for the rear, if you look in your owners manual it specifies 75W140 synthetic plus GM friction modifier.
+1 It's always been 75w140 on the 05's and 06's and 85w140 for the 04's
 

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gotta love a gto
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1,096 Posts
just went on dealer-world did not find any tsb's for different rear diff fluid. i don't know where your dealer got their bulletin from, but have them show you the tsb. and give us a #
 

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god of the sea people
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229 Posts
Discussion Starter #8
ok they were closing, so they were in a hurry, but i go back soon for the door handles and shifter rattle. i'll try to get the number then. but i have to say my diff locks up better than it ever did before.. now it really loves to drift.. fwiw.
 
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