Amsoil 75W90 Synthetic in the differential
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From: Atlanta, GA
Amsoil 75W90 Synthetic in the differential
I made a big purchase with Amsoil last week for engine oil (0W30 Signature synthetic), Transmission oil, and differential oil. I followed their recommendations and got 75W90 EP synthetic ( http://www.amsoil.com/catalog.aspx?code=SVGQT-EA ). While doing research on the forum I find that most people recommend the 75W-110 in the diff instead as it most matches the OEM spec.
Amsoil recommend a 50k change interval for this oil for "severe duty" while the OEM change interval is 30k miles.
So my question is will this oil be ok for the diff or should I ditch it and get the 75W-110? I live in Atlanta and it's fairly warm here. I don't race my car, but I do drive fairly aggressively on the street at close to stock power.
Amsoil recommend a 50k change interval for this oil for "severe duty" while the OEM change interval is 30k miles.
So my question is will this oil be ok for the diff or should I ditch it and get the 75W-110? I live in Atlanta and it's fairly warm here. I don't race my car, but I do drive fairly aggressively on the street at close to stock power.
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Joined: Sep 2010
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From: Atlanta, GA
Does anyone with direct experience with 75W90 have any comments?
Joined: Sep 2006
Posts: 7,643
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From: Irvine
i used 75w90, can't remember which brand, but my diffs started to make noises after the 2nd change. Researched the noises and found out it could lead to a blown diff. Upon recommendations from those that had the same noises, i changed to Motul 90PA and the noises went away. It's been 12k miles so far with no more noise and no blown diff for me!~
Joined: Mar 2007
Posts: 5,956
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From: Tampa
I made a big purchase with Amsoil last week for engine oil (0W30 Signature synthetic), Transmission oil, and differential oil. I followed their recommendations and got 75W90 EP synthetic ( http://www.amsoil.com/catalog.aspx?code=SVGQT-EA ). While doing research on the forum I find that most people recommend the 75W-110 in the diff instead as it most matches the OEM spec.
Amsoil recommend a 50k change interval for this oil for "severe duty" while the OEM change interval is 30k miles.
So my question is will this oil be ok for the diff or should I ditch it and get the 75W-110? I live in Atlanta and it's fairly warm here. I don't race my car, but I do drive fairly aggressively on the street at close to stock power.
Amsoil recommend a 50k change interval for this oil for "severe duty" while the OEM change interval is 30k miles.
So my question is will this oil be ok for the diff or should I ditch it and get the 75W-110? I live in Atlanta and it's fairly warm here. I don't race my car, but I do drive fairly aggressively on the street at close to stock power.
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We run the 75W-110 because the specs changed on the 75W-90 weights since the when the car came out. The 75W-110 actually is closer to the original OEM 75W-90. I cant remember the specifics but the info about the change is on here. The 75W-90 should be fine though.
Joined: Sep 2006
Posts: 7,643
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From: Irvine
anyhow, this is the thread i started a while back. I researched the forums up and down and not many people had the exact problem i had, but Kyras was kind enough to discuss this issue on the phone with me and her husband had the exact same problem : https://www.s2ki.com/s2000/topic/833...er-or-shudder/
excerpt from the thread:
As Patty (Kyras) mentioned above, I switched to the LE-1605 in my '06 S2000, and have had no problems with over 42k miles on the car now.
I had the original differential lube changed at Aliso Viejo Auto Service when the car had 13,500 miles. They used Mobil One 75W90 gear lube, and my car immediately started making rough, grinding noises during low speed tight turns. Not only could I hear it, I could feel it!
I had the mechanic check the car, and he claimed he felt nothing. 
However, it was very noticeable to myself and Patty, and she had experience with the diffy going out in her '05.
After doing some research in the S2ki "Under the Hood" Forum, I found a write-up by "Road Rage" that recommended the LE-607 Almasol which was later replaced by the LE-1605. I ordered the LE-1605 from "Ricks2k," and had Aliso Viejo Auto Service replace the Mobil One 75W90 with the LE-1605. The diff immediately stopped making the rough, grinding noises, and has been smooth as silk ever since with continued use of the LE-1605.
Unfortunately, they no longer carry the LE-1605 lube at Aliso Viejo Auto Service, so I supply it myself.
I know that some S owners have used Mobil One 75W90 successfully, but my car did not like it. I would agree that it is better to use a single viscosity lube in the differential rather than a multi-viscosity...especially in our SoCal climate. Once the car reaches proper operating temperature, I doubt there is any loss of hp.
Just my .02-worth.
I had the original differential lube changed at Aliso Viejo Auto Service when the car had 13,500 miles. They used Mobil One 75W90 gear lube, and my car immediately started making rough, grinding noises during low speed tight turns. Not only could I hear it, I could feel it!
I had the mechanic check the car, and he claimed he felt nothing. However, it was very noticeable to myself and Patty, and she had experience with the diffy going out in her '05. After doing some research in the S2ki "Under the Hood" Forum, I found a write-up by "Road Rage" that recommended the LE-607 Almasol which was later replaced by the LE-1605. I ordered the LE-1605 from "Ricks2k," and had Aliso Viejo Auto Service replace the Mobil One 75W90 with the LE-1605. The diff immediately stopped making the rough, grinding noises, and has been smooth as silk ever since with continued use of the LE-1605.
Unfortunately, they no longer carry the LE-1605 lube at Aliso Viejo Auto Service, so I supply it myself. I know that some S owners have used Mobil One 75W90 successfully, but my car did not like it. I would agree that it is better to use a single viscosity lube in the differential rather than a multi-viscosity...especially in our SoCal climate. Once the car reaches proper operating temperature, I doubt there is any loss of hp.
Just my .02-worth.