Gear oil 80W-90 versus 75W-90

Status
Not open for further replies.
Joined
Sep 26, 2010
Messages
9,134
Location
COS
My point? I said it in the first post.

So I made a table in which it is visible that 75W-90 is not always identical or better with the specced 80W-90.

Also, the wear of gears, while pumpkin is warming up, or in cold ambient weather, might be higher than the one at operating temperatures, when dilation makes things tighter.
That certainly is true for engines in warm-up condition.
Since synthetics perform better than conventionals in extreme cold and hot, have you proven your point? If you are trying to say that 80W-90 outperforms 75W-90 by using viscosity numbers at 40C for various lubes, I would say you have not proven anything.

Also, for the text I bolded, are you referring to wear that potentially could happen due to conventional oil not flowing as well as a synthetic in cold temperatures?
 

SoNic67

Thread starter
Joined
Jun 6, 2015
Messages
488
Location
VA, US
f you are trying to say that 80W-90 outperforms 75W-90 by using viscosity numbers at 40C for various lubes, I would say you have not proven anything.
I am not trying to prove anything.
It's a fact, supported by those datasheets, that at 40C, the 75W-90 is worse than 80W-90. Only 75W-110 is equal to specified viscosity at 40C.
 
Joined
Sep 26, 2010
Messages
9,134
Location
COS
I am not trying to prove anything.
It's a fact, supported by those datasheets, that at 40C, the 75W-90 is worse than 80W-90. Only 75W-110 is equal to specified viscosity at 40C.
Worse how? Less viscosity? More wear? What? You will have one heck of a time using that sheet to prove that 75W-90 is "worse" than 80W-90 in anything other than being a different viscosity at that temperature.

Also, answer the questions being posed, you keep avoiding them.
 

SoNic67

Thread starter
Joined
Jun 6, 2015
Messages
488
Location
VA, US
Also, answer the questions being posed, you keep avoiding them.
Less viscosity than what manufacturer specified, at normal range of temperatures, is worse for me.
You can use anything you want, cooking oil if you like. I don't need to defend anything, I just posted a table, you are an adult, make your own choices.


PS: I don't care about -50C, I never experienced that. And never will with my car.
 
Joined
Sep 26, 2010
Messages
9,134
Location
COS
Less viscosity than what manufacturer specified, at normal range of temperatures, is worse for me.
You can use anything you want, cooking oil if you like. I don't need to defend anything, I just posted a table, you are an adult, make your own choices.


PS: I don't care about -50C, I never experienced that. And never will with my car.
I can and I do. I just wanted confirmation that you had nothing to backup your claims of "worse" whereas millions of axles running down the road with 75W-90 keep doing so on a daily basis so thanks for the clarity.
 

SoNic67

Thread starter
Joined
Jun 6, 2015
Messages
488
Location
VA, US
Sure, I have nothing but data sheets.
As opposed to wild claims that "millions are running without problems" that are backed only by hearsay and wishful thinking.

Nobody would come here and blame the fluid that they choose, when their axle blows up. Because that would be admitting they made a bad choice and that cannot be happening.

PS: Don't bother to reply, I won't even see it, because will use the "ignore" function.
 

4WD

Joined
Sep 21, 2010
Messages
18,474
Location
Texas
Sure, I have nothing but data sheets.
As opposed to wild claims that "millions are running without problems" that are backed only by hearsay and wishful thinking.

Nobody would come here and blame the fluid that they choose, when their axle blows up. Because that would be admitting they made a bad choice and that cannot be happening.

PS: Don't bother to reply, I won't even see it, because will use the "ignore" function.
AAM - in conjunction with Eaton and GM made the recommendation of what goes in my axle …
I use both 75w90 and 80w90. Not sure why this is getting so emotional …
 
Joined
Apr 18, 2013
Messages
841
Location
Kevil,Ky
I still remember trying to shift my non-syncromesh gear box on my 1929 Model A on a cold morning. those had 600 wt gear oil.
 

4WD

Joined
Sep 21, 2010
Messages
18,474
Location
Texas
who here has actually worn out a differential? i have broken a few but no fluid in the world was gonna protect a BOP 8.2 from a 6000 rpm clutch drop. i mean don't most go at least 200k on the factory fill?
Me … complete viscosity break down after just 32k on a Pennzoil 140 dino … 2002 Dodge with only 62k …
 

4WD

Joined
Sep 21, 2010
Messages
18,474
Location
Texas
This is one I put in the Tahoe … 14.2 IIRC … think it’s likely a Grp2+/Grp3 product based on viscosity and Chevron putting the IsoSyn badge on the bottle. The ESI stands for extended service interval … good price …

737CA832-A9B2-48ED-96DE-3957D06017C3.jpg
 
Joined
Sep 26, 2010
Messages
9,134
Location
COS
Sure, I have nothing but data sheets.
As opposed to wild claims that "millions are running without problems" that are backed only by hearsay and wishful thinking.

Nobody would come here and blame the fluid that they choose, when their axle blows up. Because that would be admitting they made a bad choice and that cannot be happening.

PS: Don't bother to reply, I won't even see it, because will use the "ignore" function.
You post a table with viscosities and then claim that 75W-90 is "worse" than 80W-90 with no other supporting data and expect everyone to accept that, evade pointed questions, and then deflect when you are called out about it?

The only wild claims being made here are by you, for example:

If an open differential gets much hotter than 20C over ambient, IMO there is something very wrong with it.
 

SoNic67

Thread starter
Joined
Jun 6, 2015
Messages
488
Location
VA, US
Chevron putting the IsoSyn badge on the bottle. The ESI stands for extended service interval … good price …
That's a nice one! I didn't see it...
140cST at 40°C and 14.2 cST at 100°C.
Flash Point, °C(°F) 210(410) is pretty high too.

What is ISOSYN ® Technology? Using our expertise and experience, we combine premium base oils with high-performance additives to deliver engine parts protection that rivals synthetics.
Rather than using conventional solvent dewaxing technology, we make base oils with Chevron’s ISOCRACKING and ISODEWAXING catalyst.
 
Last edited:
  • Like
Reactions: 4WD
Status
Not open for further replies.
Top