AMSOIL or RP in diff

[Civardi]

Going to change out the diff fluid this weekend and reading through the old treads its was personal preference. Seems like most people not using GM are using AMSOIL. Give me some tips on what to buy or not to buy.

[calicadi]

I have a 2004 with the original diff still quiet as a tomb... I use Redline. Swapped out the OE fluid @ 8K mi.
http://www.redlineoil.com/

[Civardi]

Originally Posted by calicadi

I have a 2004 with the original diff still quiet as a tomb... I use Redline. Swapped out the OE fluid @ 8K mi.
http://www.redlineoil.com/

I noticed that name a couple of times as well. Are you using the synthetic and what weight?

[rangerrob]

i'm getting ready to throw royal purple in mine at the end of the week.

[NormV]

RP 75w90 then switched to 75w140 for kicks. Still a little purr around 50 mph but most passengers don't know the difference. 75w @ 12K miles, now have 31K total miles. Switched to 140 about 1500 miles ago. Three road course days and all is well. Cheap insurance for $20.


Norm

[peter simov]

see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

[silverAg]

good info in this thread since i'm ready to replace mine

[Civardi]

Originally Posted by peter simov

see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

Do you drive it in the colder weather? I don't think I would ever be out when its under freezing plus we dont get that cold up her in the northwest.

[NormV]

Good news!


Norm

Originally Posted by peter simov

see i started with the rp 75-140 and still could hear the whine but then i changed to rp 85-140 and is soild and quite as a rock so far so good 2000mi

[Dennisscars]

I've been changing diff with RP at every engine oil change when I was tracking car, I figure there's alot of Hp going through 1.5 qts. Recently have had to put friction modifier to stop chatter even though it says it has it in it. Otherwise happy with RP.

Original diff with tracked maggied car..

[GMBOUND]

I just bought Amsoil, a couple of hours ago.

[C66 Racing]

Been using the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 in my 02 Corvette Z06 track car since 2004 without any diff failures in something like 30 races and about a dozen or so driver's ed type weekends. Put the same fluid in my 06 CTS-V last year and have been very happy with it.

I do not use extra additive with this fluid as it already has friction modifier in it and neither of my car's diff's chatters. I did the diff seal recall about a month ago and they changed the fluid to GM fluid and my car's diff chattered driving it off the lot. I suspect, but don't know, that they left out the additive (which the GM fluid requires). I changed to AMSOIL, did a bunch of figure 8s and it was quiet for a day or so, then I experienced some chatter. I was going to add some additive, but by the weekend, the chatter had stopped and it hasn't come back. I suspect it took a few more tight turns than I expected to work the new fluid into the clutch packs.

Without trying to start a fluid war, some will find this AMSOIL sponsored gear lube test interesting. Both Red Line and Royal Purple were included.
AMSOIL Gear Lube “White Paper” (2 MB pdf file)

[trukk]

FYI, I would NOT recommend putting in Mobil 1. I added it,m and it has caused my plutch packs to grind on low speed turns. This is with the GM friction modifier added for good measure.

-Chris

[CTSV_Rob]

AMSOil without the friction modifier in my Diff and no whine.

[JonCR96Z]

I run AMSOIL with no noise, but I never heard any from the GM stuff either.