Lab test results of five 75w90 gear oils

[SubieRubyRoo]

PDSC is an oxidation metric. Higher is better. Brookfield is viscosity, lower is better. 4-ball wear test is low-load equivalent, similar to highway driving; 4-ball weld test is a high-load test similar to shock loading or drag racing.

TL;DR- all of these gear oils are VERY good; some are a little better at certain things, but if you bought one there’s not much lost by waiting to drain for another choice.

 

[JXW]

Why are pour points so extreme?

 

[benjamming]

Which test lab?
I assume recent formulations
What is KRL?

 

[Astro14]

Which test lab?
I assume recent formulations
What is KRL?

KRL is a measure of shear stability.

 

[dkryan]

What’s really noticeable is the wide variance on the “PDSC” number between the first two fluids and the last three.

It makes me question whether the test result for that metric is accurate.

 

[drtyler]

Amsoil Severe Gear 75W-90 looking good.

What is the difference in Differential Life and Differential Life CC?

 

[Pablo]

What is AMS oil? One word Amsoil.

Makes me doubt this. Link to original report?

 

[SubieRubyRoo]

What is AMS oil? One word Amsoil.

Makes me doubt this. Link to original report?

Not sure why lab noted it as AMS oil. This was a quart of Severe Gear that I personally delivered, along with the Redline sample from @ford250. The HPL and Motul results were from my previous thread/test, and the lab included the Mobil 1 results since they had recently run that.

 

[SubieRubyRoo]

What’s really noticeable is the wide variance on the “PDSC” number between the first two fluids and the last three.

It makes me question whether the test result for that metric is accurate.

It’s an ASTM standard.

Standard Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)

Significance and Use 4.1 Oxidation induction time, as determined under the conditions of this test method, may be used as an indication of oxidation stability.2 This test method is faster than other oil oxidation tests and requires a very small amount of

www.astm.org

 

[SubieRubyRoo]

Amsoil Severe Gear 75W-90 looking good.

What is the difference in Differential Life and Differential Life CC?

CC is their PAO-based lube, @High Performance Lubricants referenced this in my first thread which only contained results from the Motul and the HPL.

 

[SubieRubyRoo]

Why are pour points so extreme?

It’s determined by the base oils each manufacturer chose. HPL alluded to PAO in their cold climate offering; not sure what oils & additives the other brands are using.

 

[Pablo]

Not sure why lab noted it as AMS oil. This was a quart of Severe Gear that I personally delivered, along with the Redline sample from @ford250. The HPL and Motul results were from my previous thread/test, and the lab included the Mobil 1 results since they had recently run that.

Thanks. I didn't know this was something you were running. I wrongly assumed this is something grabbed from the interweb.

 

[SubieRubyRoo]

Pablo, were any of the results out of line for the Amsoil from what you think should have been expected? I was pretty impressed with the 4-ball, I think the result was even lower than when Amsoil used to publish the results for the gear oils IIRC.

 

[SubieRubyRoo]

Thanks. I didn't know this was something you were running. I wrongly assumed this is something grabbed from the interweb.

Nope, like noted, other than the Mobil result, these are all samples I gave to the lab.

 

[Pablo]

Pablo, were any of the results out of line for the Amsoil from what you think should have been expected? I was pretty impressed with the 4-ball, I think the result was even lower than when Amsoil used to publish the results for the gear oils IIRC.

I haven't compared. Wife is waiting for me to move a bench right now

 

[Pablo]

PDSC is an oxidation metric. Higher is better. Brookfield is viscosity, lower is better. 4-ball wear test is low-load equivalent, similar to highway driving; 4-ball weld test is a high-load test similar to shock loading or drag racing.

TL;DR- all of these gear oils are VERY good; some are a little better at certain things, but if you bought one there’s not much lost by waiting to drain for another choice. View attachment 152093

Amsoil Typical: (75W-90):

Kinematic Viscosity @ 100°C, cSt (ASTM D445) 16.0
Kinematic Viscosity @ 40°C, cSt (ASTM D445) 97.8
Viscosity Index (ASTM D2270) 175
Brookfield Viscosity, cP @ (°C) (ASTM D2983) 61,940 (-40)
Flash Point, °C (°F) (ASTM D92) 222 (431.6)
Pour Point, °C (°F) (ASTM D97) -43 (-45)

 

[dkryan]

It’s an ASTM standard.

Standard Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)

Significance and Use 4.1 Oxidation induction time, as determined under the conditions of this test method, may be used as an indication of oxidation stability.2 This test method is faster than other oil oxidation tests and requires a very small amount of

www.astm.org

Okay. It’s an ATSM standard.

But is anyone else wondering why there is such a difference in the PDSC values?

 

[RDY4WAR]

Okay. It’s an ATSM standard.

But is anyone else wondering why there is such a difference in the PDSC values?

That wide variance is common. It's a matter how much the brand cares to prevent oxidation. The use of anti-oxidants and better base oils show up in a good way in that test. The oils that tested much lower, that's common values of many base oils by themselves. It's unlikely that any top treatment was added to those oils in terms of oxidation prevention.

 

[Torrid]

Not too well versed in gear oils but based on recommendations of other 04-06 GTO owners I ran Torco RGO 85w140 in that car. I've never asked around here. Does Torco have a good reputation?

 

[The Critic]

How much would it cost you to get an additional oil tested?