Redline 75w90 Gear oil vs Amsoil Severe Gear 75w90? consensus best?

Joined
Sep 23, 2017
Messages
400
hey guys! out of these two gear oils, which do u think is the best.
my diff didnt really get many fluid changes over its lifetime so its kinda abused and i am hoping running the best fluid will maybe extend the life a little bit.

its a gm rear differential on a hummer h2, i just do normal city driivng and highway driving but it had dirty fluid in it for a while and when i checked recently it was low on fluid because mr lube didnt fill it properly, so thats why i want to give it extra pampering. not really trying to extend oci's or anything


are these fluids very similar that the difference is too miniscule to tell?
what are the base oils etc?

i am leaning towards the amsoil just because the gear oil is in a bag and its easier to squeeze and pour but if redline is indeed better or technically supposed to be better then ill go with that!

thanks
 
Last edited by a moderator:
Joined
Mar 21, 2004
Messages
26,400
Location
Upstate NY
No experience with Redline. But Amsoil SVG in every differential when I change the gear oil. I would guess they are both very high quality gear oils.
 
Joined
Jan 26, 2020
Messages
25
Location
Duluth, GA
There are a fair amount of UOAs on BITOG of Amsoil’s Severe Gear. From what I recall SVG does very well. As compared to Redline, I’m not sure.

I believe both Amsoil and Redline make very good synthetic gear oil.


East Coast Gear Supply do not recommend Full Synthetic gear oils, but makes an exception for Amsoil and Redline. I think it is safe to say that either one of these top shelf gear oils will serve you well.

Also, what is your specific application for the gear oil? That may help others in their recommendations for you.
 

jalikaria24

Thread starter
Joined
Sep 23, 2017
Messages
400
thanks for the reply!
its a gm rear differential on a hummer h2, i just do normal city driivng and highway driving but it had dirty fluid in it for a while and when i checked recently it was low on fluid because mr lube didnt fill it properly, so thats why i want to give it extra pampering. not really trying to extend oci's or anything
 
Joined
Nov 3, 2013
Messages
1,647
Location
UT
No experience with Amsoil, but I have Redline 75W-90 in the rear diff of my E350. Redline is what FCP Euro, which specializes in parts for European cars, recommended for my Mercedes.

I have been very happy with it's performance, and would have no problem recommending it to others.
 
Joined
Nov 18, 2007
Messages
181
Location
NJ
REDLINE for sure!! ESTER based is the best + since SCAMSOIL moved away from true synthetics + answer NO questions a CALL to REDLINE will tell the TRUTH!!
This guy again? Didn't your parents teach you that if you don't have anything nice to say, don't say anything at all?

Amsoil could be created by God and you would still be adding your worthless comments about how it is terrible.

With that said, I have used Redline MT-90 in 2 cars. A 95 Pathfinder and a 2004 A4 6spd. Both in the trans. Both times it was absolutely terrible. I have used Amsoil in my A4 and 2001 S4. I had the severe gear in my A4 rear diff, had the regular in the front diff. In my S4, I have Amsoil FGR in the front diff, MTG in the rear diff, and the older regular (before signature) ATF in my trans plus AFL in the engine. I have no issues. I'm going to tell you that Amsoil is the best but it has worked out for me in my cars. My 2 new subarus are under warranty and other than using some M1 0w-20 AFE everything is OEM. My wife's CR-V is using M1 EP. I also have 6 boxes of M1 0W-40 for my S4 since I got a good deal at Costco a while ago.

From what I have seen here, severe gear gets great reports. And to show I am NOT against redline I would like to try either 0W-40 or 5W-40 or both in my S4 and the 0W-20 in the honda and/or Subarus in the future.
 
Joined
Aug 23, 2010
Messages
3,180
Location
pa
just to add when i got my new to me Nissan Frontier SV 4WD 6 spd manual with about 30 thou on it i changed ALL drivetrain fluids to Redline + switched to their 75-90 from nissans 75-140 seni syn in the rear + netted 2- mpg's
 
Joined
Oct 27, 2018
Messages
465
Location
MD
In my previous Maxima 2002 6 speed MT, I used Amsoil 75w90 and it made a world of difference in smooth shifting. The stuff WAS AMAZING.
 
Joined
May 21, 2018
Messages
2,679
Location
South Carolina
I just use SuperTech 75w-140 in my old junks that require 75w-90. Very happy with the decision. Better than Mobil1 75w-90 by the way. Mine may be old junks but I take my decisions seriously because I keep them forever.
 
Joined
Sep 26, 2010
Messages
9,110
Location
COS
I have not tried Redline, but have used Amsoil (75W-110 and 75W-140) since 2010 and it has performed very well. I believe that @buster noted that Amsoil also has quite a bit of ester in it. IMHO - Amsoil gear oil is the best thing they do and is arguably the best gear oil on the market.
 
Joined
Jan 16, 2017
Messages
959
Location
Palmer, Alaska, USA
Don't know!
Still a fan of Mobil 1 75W-90 LS synthetic gear oil.
It does an outstanding job and I don't want to pay extravagantly for the "best."
 
Joined
Apr 10, 2005
Messages
534
Location
Middle Tennessee
I recommend Red Line. I have been using Red Line 75W90 GL5 for a long time and have had zero issues. I even use it in the trans and primary in my Harley Davidson Sportster with good results. The tech at Red Line says this gear oil does not harm yellow metals so is safe in multiple uses.
 
Joined
Jul 23, 2005
Messages
321
Location
ohio
We have used both extensively. In a differential they are both superb. For our transaxle/gearbox usage the Amsoil provided better shifting operation.
 
Joined
Dec 31, 2017
Messages
9,942
Location
SE British Columbia, Canada
I see others are offering alternatives so I will too. I used Delco 75w90 synthetic for two changes and Motomaster 75w90 synthetic for one change on a 14 bolt rear end on my 3/4 ton Chev that towed 7,000 lbs occasionally. I owned it since new and it has over 200,000 miles. No problems.
 
Top