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

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Sep 23, 2017
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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
 
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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.
 
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
 
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.
 
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.
 
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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
 
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.
 
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.
 
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.
 
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."
 
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.
 
We have used both extensively. In a differential they are both superb. For our transaxle/gearbox usage the Amsoil provided better shifting operation.
 
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.
 
I have used both. There is no way I can tell any difference in gear oil. I just use Amsoil now because I got a local dealer and I like him and his wife.
 
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