What does sulfur do in an oil?

[brianpavlovic]

I am comprising my "Black Book List of Oils" that I am thinking about running and in my quest, some oils have sulfur in them and some do not!! For example, Mobil 1R has over 4000ppm and Motul 8100 0W-40 has over 1700ppm while Lubro Moly 0W-40 as well as Amsoil have 0!!!! Is Sulfur a good thing in an oil or a bad thing and what does it do?

-Brian

 

[haley10]

I'm not an expert, but I'll venture a guess until you get a real answer.

It's a protective additive, probably used as a metal deactivator. It would reduce the catalytic effect of metals on the oxidation rate. It might be an oraganic complex containing sulphur.

I wouldn't call it good or bad. The ones with zero just achieve it some other way.

 

[brianpavlovic]

Uh, can you put that in simpler terms for me! I am very wet behind the ears when it comes to oil!

 

[JHZR2]

The GM-LL-025-A oil that came factory fill in my 04 Saab 9-3 (I am almost positive it is elf excellium 0w-30), has a high sulfur content.

The GM-LL spec oil is designed for 32k km drain intervals in gas engines, so it would make sense that it is some sort of metal deactivator, or something of that sort.

JMH

 

[Pablo]

S is native in petroleum. You can smell it! Most refineries have sulfur removal processes. Petroleum based oils will always have some sulfur.

Some/many additives have sulfur. MoTDC where the T = thio, meaning sulfur. It's a compound, the S is not free to roam about.

 

[haley10]

quote:

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Originally posted by brianpavlovic:
Uh, can you put that in simpler terms for me! I am very wet behind the ears when it comes to oil!

---

No, I can only make it more difficult by saying it could also be an EP/anti-wear agent as well. Have you looked at Bitog's mainpage and clicked on the Lubrication Design box?? There is some good general info about additives.

 

[Ken2]

Sulfur is bad. It is one of the contaminants that kill catalytic converters, phosphorus being the other.

Sulfur is good...when it is chemically combined with other elements as the "thio" in zinc dialkyldithiophospate antioxidant and antiwear agent, molybdenum dialkyltrithiocarbamate antiwear, and related chemical compounds.

Environmental agencies around the world are forcing oil makers and engine makers to use oil lower in total sulfur. With sulfur in fuel now reduced so much, sulfur in burned oil is making a difference.


Ken

 

[Ray H]

Sulfur, in the form of additive oxidation products will also combine with accumulated condensation in the sump. Guess what kind of acid it forms . . .

 

[MolaKule]

Most of the sulfur in synthetic oils come from the additive ZDDP which is Zinc dialkyldithiophosphate, and and in other dithio's such as dithiocarbamates (MoDTC, SbDTC, etc) where the "thio" are the sulfur atoms.

In mineral (conventional) oils, the sulfur is naturally occurring. Some sulfur may come from friction modification additives as well, if used.

Sulfur is a polar molecule, acts as an antiwear component and helps to dissolve additives (make them more miscible, to a point).

Too much sulfur in the crankcase can form sulfuric acids, but most PCMO's contain additives that inhibit or reduce the sulfur molecules from becoming corrosive; these additive are the "overbased" detergent's.

See this thread for a comprehensive list of additives:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=21;t=000032

 

[jimcor]

Most motor oils use sulfur because you can't put beans in your engine. Beans would make your **** can Honda really sound good, but such is life. So to make up for it they use a 'chemical bean'...sulfur. If you don't own a **** can Honda or other similar machine you don't need no stinkin' sulfur.

Just kiddin'!

Wow, that's an editor! Gas passing, wind breaking, cheese cutting.