EP Additives in Gear OIls

[Jim Allen]

After doing some further research, here are more questions/comments on EP packages.

1) Which are "better," irrespective of cost for the purposes of this discussion,chemical EP packages like Sulphur/Phosphorus (S/P)or the dispursed additives like Moly or Calcium/Borate or ?

2) If the common S/P package "breaks down" or "decomposes" at 250-275 degrees, what happens to the material?

3) Are there S/P EP packages that have higher thermal limits than 250-275?

4) Not picking on them in particular, but I notice that Amsoil lists thermal stabiliy of over 300 degrees with it's gear oil, but is that claim based only on the PAO base stocks or does it include the EP (iron/sulphates)package? Or does their EP package fade away before the base oil as some claim?

 

[MolaKule]

1) None are better than the other but work best if carefully formulated into a synergistic package.

2) What is your definition of "break down" or decompose???

3) Yes, and we use them in our racing mid-viscosity HDS-R.

4) Thermal stability of the base oil or what, and what does Amosil define as thermal stability?

 

[bruce381]

1. S/P offerers better Anti Scuff protection where Moly would be FM mostly and Borate is a good Anti Wear aswell as a TBN booster.

Most good gear oils will use a S/P base with either moly or borate added to enhance the perfromance I perfer Potasium Borate.

2. When most any additve "breaks down or Oxidizes it will form an acid salt of it self and will lead to corrosion, sludge, varnish and even a reduction of wear protection.

3.Yes they are stable and have high AO content aswell as lower "EP" activity meaning more is used in the oil for the same effect again Borate is great for this.

4. do not know ask Amsoil.
bruce

 

[Jim Allen]

Thanks for the answers gents.

MolaKule: In number 2, I am wondering what happens to the EP package at the higher temps. "Common knowledge" is that S/P EP packages become acidic, as bruce 381 states, and its effectivness as an EP additive is reduced starting at 250 degrees. I'm trying to confirm or deny if 275 degrees is a good maximum rule of thumb number or can some oils/ad-packs do better. I'm aware that oxidation increases with heat but am trying to find a gneral rule that will fit most gears oils, or perhaps a few general rules to suit the different types.

As to Amsoil, I'm trying to arm myself with a little independant knowledge before I ask... a ** detector if you will. I am unclear what thie stated "Iron-Sulfide" EP package is about.

bruce381: Since you seem so knowlegible about the Chevron products, is it true that their ESI range of gear oils use all group III base stocks, as their website seems to indicate, or is it a mix of II and III as one person just told me.

MolaKule: The synergystic concept is one that I have recently come to grasp. It helps me get past the ad hype and to stop focusing so much on the individual elements in an oil (good or bad), but to concentrate on how the entire package works together. That makes it harder to debate the finer points pedantically as we are prone to do in this forum and for ad guys to really sink their teeth into.

 

[bruce381]

"bruce381: Since you seem so knowlegible about the Chevron products, is it true that their ESI range of gear oils use all group III base stocks, as their website seems to indicate, or is it a mix of II and III as one person just told me."

I do not work at Chevron but know of the "borate" package they use as far as base stocks Chevron makes both GPII and GPIII at Richmond BUT they are all lower vis other than the 600N which is still low as far as a gear oil goes my guess is they use "150 bright Stock" from Exxon as a Thickener for heavy gear lubes. altho I forgot who but someone has a GPII bright I think.

bruce

 

[bruce381]

"bruce381: Since you seem so knowlegible about the Chevron products, is it true that their ESI range of gear oils use all group III base stocks, as their website seems to indicate, or is it a mix of II and III as one person just told me."

I do not work at Chevron but know of the "borate" package they use as far as base stocks Chevron makes both GPII and GPIII at Richmond BUT they are all lower vis other than the 600N which is still low as far as a gear oil goes my guess is they use "150 bright Stock" from Exxon as a Thickener for heavy gear lubes. altho I forgot who but someone has a GPII bright I think.

bruce

 

[MolaKule]

In a good formulation for EP gear oils, enough acidic fighting chemicals are included to prevent the lube from increasing the TAN for at least 50,000 to 75,000 miles, depending on driving conditions such as trailering, no trailering, etc.

Most modern gear lubes contain anti-rust, anti-corrosion, and metal deactivators to prevent the sulfur in the EP package from becoming "active" at attacking the metals, but still allowing the sulfur to form the necessary protective layter to prevent galling and wear.

See this tech brief for more info. It's buried in the Interesting Articles thread under the "Science and Technology of Oils and Additives" section:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000227

For our 75w90 gear lubes, we find that when the lube TEMP gets above about 295 F, the Fe wear increases about 5 ppm/per every 10 degrees rise over that temp. You would only see this in racing such as NCAR circle track racing where they do not use diffy oil coolers. In NASCAR events, they are allowed to use diffy coolers.

For daily drivers, you might see the fluid reach 210 F max on a hot day. Even while pulling a load of wood one day during the summer, our PathFinder's diffy never went above 200 F with our HDS-5 75W90. Synthetic GL Fluids that contain Friction reducing additives (such as ours) typically keep the temp in check.

Our mid-viscosity HDS-R was run in middle-of-the-summer conditions in NCAR modified circle track racing and showed temps of 30 F less than the 75W140 Blend that had been used prior to changeover.

quote:

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...stated "Iron-Sulfide" EP package is about.

---

Most S-P (EP) packages form iron-sulfide and iron-phosphide protective layers at the gear tooth, so in my opinion, this is simply stating the obvious for those who have insight to the tribochemical conditions of gear lubes. For the public unaware of tribochemical conditions at the tooth level, this might appear to be something new.

 

[Jim Allen]

This is JUST what I was looking for to clear that roadblock in my head! No oil, regardless of base stock, is immune to the effects of temperature. The goal is to reduce the operating temp as much as possible, partly through the use of friction reducing additives, and mostly via mechanical means like coolers, finned covers, oil capacity, etc. I've been running some tests on my truck and the diff runs at 170 at freeway (65mph) speeds at 60 degrees ambient. It's a low geared truck, so it runs a bit hotter that other rigs might. With a 10,000 pound test load, well, I'm getting some pretty high temps... nearing 250 in 15 miles on flat ground at 45mph. I recently pulled 12 tons of grain (I farm on the side) in two big grain wagons and reached nearly the same temp in just four miles. I will be putting in two other types of oil and checking how the temps are effected. Then, I will be installing a finned cover that increases oil capacity and surface area and running the same tests with all three oils.

Thanks for the info!

 

[MolaKule]

I would only add one more point in that carefully selected bastocks containing synthetic fluids offer better low temerature operation on the one end, and resist thinning and oxidation on the high end much better than do mineral-based oils.

And since mineral-based oils of Group I and II contain active sulfur, with synthetic based oils we can control the sulfur and deactivate it in terms of corrsosion protection.

The more oil you can have in the sump, and the cooler you can keep the unit, the less oxidation you will see in the lubricant and increase it's longevity.

 

[bruce381]

"And since mineral-based oils of Group I and II contain active sulfur, with synthetic based oils we can control the sulfur and deactivate it in terms of corrsosion protection."

Huh? while a old style GPI solvent extracted base oil can have 3,000-4,000ppm sulfur most GPII oils have less than 10ppm and at that level They are not in a practicle sense or even with ASTM tests "active".
bruce