I have a 2005 ram 5.7 hemi 4x4

Rear differential build is.

Axle Ratio 3.55

Corporate 9.25 LD

Can I use the Mobil 1 full synthetic rear Differential Fluid that already has the LSD additive already in it ?

If I cant find the Mobil 1 fluid that does NOT have the LS additive package IN IT.

I would like too use the Mobil 1 full synthetic. in my rear differential.

Thanks .

 

Yes you can, whether it has LSD or not (you did not say it did), as long as it is the correct weight.

 

Thankyou.
That's all the info I have from the build sheet.
So I'm not for certain I have LSD rear diff or not.
​​Thats why I'm asking if a LSD fluid would harm an open non LS rear differential ?

 

The additive will NOT harm a NON lsd diff.

The LACK of additive WILL harm a lsd diff.

 

Mobil 1 gear oil with LS additive will work fine in your rear diff, whether you have LSD or not.
You probably don't have the LSD rear end, it would be listed as "anti-spin" on your build sheet if it was installed. Most 3.55 rear ends do not have LSD.
Easy way to tell will be when you take off your diff cover to drain the gear oil, if there is a clutch pack then you have the anti-spin.
If you want the most protection possible for an open diff, you can get the gear oil without the friction modifier online and from Walmart. I would recommend this if you do a lot of towing or keep your bed loaded. The LS additive gives up some high pressure qualities to reduce friction in the clutch pack.

 

JRSlick . Fantastic write-up it really clears things up nicely. Thankyou.

I did order the Taylor plug wires for no other reason other than asthetics. Went with red.

 

IF your rear end is stock and has LSD, then the build sheet will have a an item like this: * Anti-Spin Differential Rear Axle

This^^