Another gear oil question - Castrol and Valvoline 75w90

Mossyoakglock · March 8, 2012

I am trying to find out if the Castrol and Valvoline 75w-90 synthetic has the limited slip additive already mixed with it. I searched but couldn't find a straight answer.

I know Mobil1 has the Limited Slip additive already mixed in since it has a big LS on the front. I was looking at the Castrol 75w-90 at the store the other day and there was no mention anywhere on the bottle that it actually contained a limited slip additive. It did say that it was ok to use in limited slip applications so it lead me to believe it had it, but again there was no mention of it already being blended in.

As for the Valvoline, there was one post that said somebody called Valvoline to ask if it met the GM spec and they said that their Valvoline SynPower synthetic meets the GM spec which leads me to believe that it does not have the additive blended in.

Does anybody know for sure? I'm using Castrol DEV VI in both my transmission and transfer case and have been very pleased with it so I thought I would stick with Castrol on the rear end as well.

Thanks!

txab · March 8, 2012

IF you have a G80 then you do not need a limited slip additive

http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9012214&contentId=7036190

Mossyoakglock · March 9, 2012

I have the G80 which is why I was asking if either of these had the LS additive because I don't need it.

I've been running Mobil1 which has the LS additive in it with no problems but if I could find something that did not have the additive (and wasn't $30 a quart) I was going to run that. But, it seems that all 75w90 has the LS additive already in it so I might as well stick with Mobil1.

txab · March 9, 2012

$15 per qt. No additives

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

ChevyTech77 · March 9, 2012

$15 per qt. No additives

http://www.amsoil.co...efront/svg.aspx

My recommendation as well. Get rid of the lube with LS additives in it. It's playing hell with your factory G80 diff.

Mossyoakglock · March 13, 2012

How good is the Redline gear oil? They make a 75w-90 synthetic in both limited-slip and non-limited slip and I can get it locally so I don't have to worry about shipping costs.

Price per quart is the same so I would be saving on shipping cost and time.

dlstewart01 · March 13, 2012

Red line is a true synthetic Ester based oil. Many racers swear by it.

redjewel2ss · March 13, 2012

where are you getting Mobil1 for $30 per quart? i bought it about a year ago for my camaro for around $12 a quart at a local parts store. amazon has it for $12 a quart right now.

dlstewart01 · March 13, 2012

I have been using Castrol Syntec 75/90 in my G80 for 7 years with no issues what so ever.

Mossyoakglock · March 13, 2012

where are you getting Mobil1 for $30 per quart? i bought it about a year ago for my camaro for around $12 a quart at a local parts store. amazon has it for $12 a quart right now.

I meant to say I didn't want to spend $30 a quart on the GM stuff when I can get Amsoil or Redline for $15 a quart. I'm using Mobil1 right now but since it contains the limited-slip additive I don't want to run it anymore since the G80 doesn't need it. Redline makes a non-limited slip gear oil that I'm going to use.

I called Amsoil yesterday and the tech that I talked with said that their Severe Gear 75w90 does contain some friction modifier which I found odd because I was under the assumption that it did not.

Edit: Sent an email to Tech support today asking them about the Long Life gear lube. They said that if I need a gear oil and do not need any friction modifier to use the Long Life Gear Oil in my truck.

Mossyoakglock · March 14, 2012

After much research, this is what I have come up with. Most of this is from bobtheoilguy.com:

"Automatic Locking Differential Lubricants. [Note from Michael Asmussen, Torque Control Products Division of Eaton Corp.] We recommend the following lubrications for our locking differentials:

1)Texaco 2276; Synthetic 75 W90; Gm Part # 9986115

2)Texaco 9622; Mineral based 80W90; GM Part # 9985290

3)Texaco 2080; Synthetic 75W140 (heavy duty applications); GM part # 9985991

Note - All of the above lubes are preblended with friction modifier. No additional modifiers are necessary or recommended. As far as other lubes are concerned, any standard GL 5 lube will work, but the units perform optimally with the three listed above.

From another post:

From Mobil1

No, you must procure this product at your local dealer.

---------------------------------------------

From Amsoil

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From the GM Regional Rep

The spec is for friction modifier to be included in the oil versus two separate bottles. So basically it is a packaging/purchasing spec only. As long as your choice meets API GL5 specs and has the friction modifier your good to go.

From what I can find, it sounds like the GM fluid actually has some friction modifier already add but the addition of any additional friction modifier is not needed and that any GL-5 rated fluid will work.

Since the Amsoil Severe Gear has some friction modifier already blended, that seems like the way to go.