Differential oil: Amsoil or Royal Purple?

[Indy]

1999 Viper RT10 Diff Oil 75w140:

For those running a diff oil other than mopar, which one of these two is better: Amsoil or Royal Purple? Those running Amsoil, did you ad a friction modifier to the oil? It doesn't say on the bottle that is has it included. The Royal Purple does state that it is for limited slip diffs. Here are the two oils I am looking at:

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[Steve M]

I don't think you can go wrong with either, although the Amsoil pictured is only a 75w110 instead of 75w140. FWIW, I run Torco synthetic gear oil in my Gen IV.

 

[ontariomystic]

The amsoil 75w-140 says compatible with most limited slip rearends on the label. I added the amsoil friction modifier just to be safe.

 

[Indy]

although the Amsoil pictured is only a 75w110 instead of 75w140

oops...corrected that
Thanks for the replies. I think I'll go with the Amsoil. 2 bottles should be sufficient, right?

 

[ontariomystic]

2 bottles is enough, amsoil also makes a cheap hand pump that mounts right on the bottle for like $15. Worked really well compared to more expensive hand pumps i've used before. Even rigged it up in reverse to draw out the old fluid and worked perfect.

 

[Indy]

Should I also get the Friction modifier, or is there enough in the diff oil to tackle the limited slip?
Also, is AMSOIL Series 2000 Synthetic the same oil as the Severe Gear oil?
thanks

 

[Darth Menace]

I have that Amsoil in there. Didn't use their friction modifier, and no complaints either way.

 

[ontariomystic]

Should I also get the Friction modifier, or is there enough in the diff oil to tackle the limited slip?
Also, is AMSOIL Series 2000 Synthetic the same oil as the Severe Gear oil?
thanks

Could be, series 2000 is what they used to call it i think.

 

[Indy]

Thanks guys. Just ordered the Amsoil. cheers

 

[Fatboy 18]

Yep, I too run Amsoil, I did not add the friction modifier. Stock gears no problems

 

[impalassed]

AMSOil gear lube has the friction additive in it. You may add some should your diff "tell you" it wants a bit more.

 

[schabiazabi]

Neither.

Use RedLine Synthetic 75W140 Gear Oil with FM. That oil has the highest viscosity index.
Never use Mopar, factories use one of the lowest bidding products. Once the FM is in the oil already, never add more.

AMSOil does make good products here and there, but once you compare the viscosity indexes at different temperatures RedLine is
the winner.