80w-90 = dino
75w-90 = synthetic

Just a way for oil companies to let you know the difference. I believe there is non synthetic fluid in our rear diff since it calls for 80w-90. Being a limited slip does not infer it takes synthetic oil.

 

When i called the dealership parts department, they said it was dino oil.

 

I had mine changed at something like 2000 miles- there were a lot of metal shavings in there. Every 20,000 miles thereafter for me. Also change the manual transmission fluid too. May be a waste of money but good peace of mind for me.

 

When I looked around...75W90 seemed to be more readily available than 80W90. Do you think it would be ok just to use 75W90 (Mobil 1 Syn) or should I just order thru amsoil and get 80W90. I would think 75W would have better protection in the winter but perhaps it might not hold its viscosity as well as a 80W?

 

Ditto...it's dino.
The Amsoil I know of is 75w-90. Wouldn't worry about not holding it's viscosity if your going with Amsoil.
Amsoil Severe Gear (SVG) for the diff is the way to go, imo.

 

Lordco told me that nobody makes synthetic 80W-90.

 

The only 80w-90 I know of is Dino.
OEM lists their differential oil as API GL-5 SAE 80w-90.

Oh...if anyone interested more about Amsoil, and for the 6mt gearbox, their 75w-90 GL-4 (MTG) is the stuff to use.
Don't ever use GL-5 in the gearbox. You'll have issues with the syncros, possibly permanent.

Here's OEM requirements for the gearbox from my 06 service manual:
(MTF) HQ multi 75w-85 or API GL-4 SAE 75w-85 or 75w-90.

 

Amsoil does have a synthetic 80w-90 gear lube (I'm assuming it would be ok to use for the G's Diff) but after reading up on it, I think I'm gonna order the "SEVERE GEAR® Synthetic Extreme Pressure (EP) Lubricant 75W-90 (SVG)" and leave it in for 50K. I just gotta go to the stealership to get the gaskets for the diff plugs since I hear it's hard to find at parts stores. I plan on doing this at 35K while chaning the oil on the auto trans (at the dealership). For the trans I'm doing 35K OCIs.

FYI: I just changed the engine air filter at 25.8K and it looked horrendous. I'll be changing them at 20K max from now on.

Here are the links:

https://www.amsoil.com/storefront/agl.aspx

https://www.amsoil.com/storefront/svg.aspx

 

Oops...my mistake Didn't see that one on their drop down menu.
Yeah... like I said, their SVG is the way to go

 

OK, I did it today and took picks...

 

Here is the rest...

 

wow great info. thanks....

 

http://forums.freshalloy.com/showthr...smission+fluid

Here is a DYI link from FA. Just a little more info for those who are a little more OCD and want step by step directions. It's really easy, if you can do an oil change you can do this. Just make sure the care is leveled.

 

thanx for the pics. they speak a thousand words.. i was going to do my gear oil today , so you helped me ALOT with pics.. woOot woOOt. this should be a sticky!

 

Im doing mine today too! We should have had a gear oil changing party (with beeeeerrrr)