Black stuff

[Lawman]

I bought four quarts of BMW "engine lubricant" from my dealer..That's what is on the label..It looks a whole lot like oil but I know it's more than that because I paid $4.00 a quart for it..What's the black stuff in the bottom of the container that is thickest in the corners and is only readily visible after I've poured most of the contents into the crankcase of my beloved R1200RT?

[BMWRich58]

I bought four quarts of BMW "engine lubricant" from my dealer..That's what is on the label..It looks a whole lot like oil but I know it's more than that because I paid $4.00 a quart for it..What's the black stuff in the bottom of the container that is thickest in the corners and is only readily visible after I've poured most of the contents into the crankcase of my beloved R1200RT?

 

Sumptin' ain't right....

Sounds like somebody refilled the bottles with old oil. Were the "cap seals" broken??

 

Should be clear with a golden tint to it.

[DEF]

I bought four quarts of BMW "engine lubricant" from my dealer..That's what is on the label..It looks a whole lot like oil but I know it's more than that because I paid $4.00 a quart for it..What's the black stuff in the bottom of the container that is thickest in the corners and is only readily visible after I've poured most of the contents into the crankcase of my beloved R1200RT?

 

The black stuff is moly or, more accurately, molybdenum disulfide, a friction modifier that is very slippery and reduces friction especially under high loads and high temperatures. Shake well before dispensing the oil into your engine.

[Lawman]

Thanks..Good to know I'm getting more than just oil..

[RFW]

I bought four quarts of BMW "engine lubricant" from my dealer..That's what is on the label..It looks a whole lot like oil but I know it's more than that because I paid $4.00 a quart for it..What's the black stuff in the bottom of the container that is thickest in the corners and is only readily visible after I've poured most of the contents into the crankcase of my beloved R1200RT?

 

The black stuff is moly or, more accurately, molybdenum disulfide, a friction modifier that is very slippery and reduces friction especially under high loads and high temperatures. Shake well before dispensing the oil into your engine.

It is also EXCELLENT for clogging up your oil filter!

 

Given that there is no metal to metal contact in a motor's bearings in operation (they ride in a hydrodynamic oil film), there is no use in adding MoS2 (or teflon, or anything else like that) which is only useful as a lubricant between metal surfaces that have no clearance.

 

Google "Slick 50" (a lubricant that contains teflon particles) if you want to see all the problems with oils that contain solid "lubricants". Don't use this stuff! In the worst case, the MoS2 (or teflon or whatever) clogs the oil filter, resulting in the bypass valve opening, and the engine getting unfiltered oil pumped to the bearings.

 

By the way, MoS2 is NOT a "friction modifier". It is a solid lubricant that is intended to reduce the friction between metal to metal surfaces. Your bearings (as noted above) are NOT in metal to metal contact, so the stuff is useless.

 

Bob.

[1hawkrider]

....there is no metal to metal contact in a motor's bearings in operation (they ride in a hydrodynamic oil film), there is no use in adding MoS2 (or teflon, or anything else like that) which is only useful as a lubricant between metal surfaces that have no clearance...the MoS2 (or teflon or whatever) clogs the oil filter, resulting in the bypass valve opening, and the engine getting unfiltered oil pumped to the bearings.

 

By the way, MoS2 is NOT a "friction modifier". It is a solid lubricant that is intended to reduce the friction between metal to metal surfaces. Your bearings (as noted above) are NOT in metal to metal contact, so the stuff is useless.

 

Bob.

 

But, there is no metal to metal contact in either case, really. The engine bearings have the "oil" and the other metal surfaces with "no clearance" has the MoS2. I'm not an engineer, but I'm guessing that you meant "less" or "minimal" clearance, not "zero?

 

Second, why, then does BMW put the stuff in their oil and recommend its use, with a potential for engine damage?

 

Lou.

[Mark_C]

We might be in danger of over-simplifying things here. What about the main bearings from a cold start before oil pressure has built up? Isn't it true that most engine wear takes place in the first few minutes of each journey? And what about all the other bearing surfaces such as chain guides etc? Interesting what you say about the filters though. Was the oil that Lawman was given recommended by BMW or just the dealer?

[DEF]

It is also EXCELLENT for clogging up your oil filter!

 

By the way, MoS2 is NOT a "friction modifier". It is a solid lubricant that is intended to reduce the friction between metal to metal surfaces. Your bearings (as noted above) are NOT iBob.

 

Nonsense.

 

Oh, and add moly to your gear oil in your trans and rear drive. It reduces friction and heat and helps gears retain their clearances by forming a lubrication barrier that clings to metal surfaces and reduces wear. Oh, and lube your splines with EP GL5 NLGI lithium soaped grease fortified with moly (about 50% is right). It prevents the dreaded spline wear and increases spline life dramatically.

 

Oh, and BTW, moly grease is also used as a anti-seize compound. Put a bit on your sparkplugs before installing them......

[RFW]

We might be in danger of over-simplifying things here. What about the main bearings from a cold start before oil pressure has built up? Isn't it true that most engine wear takes place in the first few minutes of each journey? And what about all the other bearing surfaces such as chain guides etc? Interesting what you say about the filters though. Was the oil that Lawman was given recommended by BMW or just the dealer?

There is sufficient oil remaining in the bearings to support a minimal hydrostatic film, that is perfectly adequate at startup, since there is no load on the motar at all. If the motor runs for more than a few tens of seconds (with no pump pressure), this oil will eventually be lost, but by then your filter is filled and you have oil pressure.

 

As far as BEARING wear is concerned, there is no possibility of wear after the pump pressure has built up, and (assuming a normal start) that is a mere second or two after you hit the button. After that time, the full pressure-driven oil film is present. There is no difference in wear between the time 5 seconds after start, and 5 hours.

 

Bob.

[RFW]

It is also EXCELLENT for clogging up your oil filter!

 

By the way, MoS2 is NOT a "friction modifier". It is a solid lubricant that is intended to reduce the friction between metal to metal surfaces. Your bearings (as noted above) are NOT iBob.

 

Nonsense.

 

Oh, and add moly to your gear oil in your trans and rear drive. It reduces friction and heat and helps gears retain their clearances by forming a lubrication barrier that clings to metal surfaces and reduces wear. Oh, and lube your splines with EP GL5 NLGI lithium soaped grease fortified with moly (about 50% is right). It prevents the dreaded spline wear and increases spline life dramatically.

Gears do NOT have clearances. Gear teeth are in hard metal to metal contact. The reason they do not wear is because they use an involute tooth form that results in zero sliding contact. Gear teeth ROLL against each other. They do not slide, with the exception of Hypoid gear sets (which are not used on bikes), which require special hypoid oil that deposits a hard sulphide film (hence the sulphur stink of hypoid oils!) on the gears in operation. Because spur gear teeth do not slide against each other, a solid lubricant like MoS2 is useless as a wear or friction preventer, because there is no sliding friction in the first place. This is a fundamental mechanical engineering concept.

 

In lubrication industry terminology, a "friction modifier" is not a solid lubricant like MoS2. "Friction modifiers" are an additive to the oil that is dissolved in the oil, the most common example being ZDDP (zinc dialkyl-dithiophosphate).

 

Splnes are a different matter. BMW does recommend a 60% moly grease for obvious reasons, or a MoS2-type "bonded" (i.e. dry) lubricant. It is not a "recommendation" to use moly grease or bonded lubes here, it is a REQUIREMENT to prevent fretting wear. Their specific recommentations for spline lube is Unimoly C220 Bonded Lubricant, or one of the Staburags family of moly grease (both from Klüber Lubricants).

 

Bob.

[smiller]

Splines are a different matter. BMW does recommend a 60% moly grease for obvious reasons, or a MoS2-type "bonded" (i.e. dry) lubricant. It is not a "recommendation" to use moly grease or bonded lubes here, it is a REQUIREMENT to prevent fretting wear. Their specific recommentations for spline lube is Unimoly C220 Bonded Lubricant, or one of the Staburags family of moly grease (both from Klüber Lubricants).

Slight hijack...

 

Bob, you seem to have some knowledge in this area so... would you consider an anti-seize compound as an acceptable spline lubricant? (The factory stuff looks just like anti-seize in fact, bright silver in color, not dark like one would expect of a moly-based lubricant... although obviously appearance can be misleading. ) Splines slide against each other and don't need a high-speed lubricant, just an extreme-pressure lube that that will prevent corrosion and galling/fretting and most importantly, stay in place. Anti-seize will certainly do this... are the metallic lubricants used in anti-seize necessarily any better or worse than moly in this application?

[RFW]

Slight hijack...

 

Bob, you seem to have some knowledge in this area so... would you consider an anti-seize compound as an acceptable spline lubricant? (The factory stuff looks just like anti-seize in fact, bright silver in color, not dark like one would expect of a moly-based lubricant... although obviously appearance can be misleading. ) Splines slide against each other and don't need a high-speed lubricant, just an extreme-pressure lube that that will prevent corrosion and galling/fretting and most importantly, stay in place. Anti-seize will certainly do this... are the metallic lubricants used in anti-seize necessarily any better or worse than moly in this application?

No, anti-sieze compounds are not lubricants. They are intended to stop the growth of intermetallic compounds especially in aluminum, and also to prevent the sort of corrosion that causes parts to "weld" together.

 

The main purpose of an anti-seize compound is to stop a chemical process, not to lubricate. I wouldn't use them as a lubrication substitute.

 

You are right, that spline lube is intended to stop the kind of wear that is caused by very high pressure but almost zero movemement between parts. This is often termed fretting wear. The best defence against this is moly or graphite grease (the moly or the graphite are what does the job; the grease is just a vehicle).

 

Bonded lubricants are also excellent, and have no grease in them at all.

 

Bob.

[q2bruiser]

Moly has been around for a long time. It is found, at least in small concentrations, in most all auto oils although it is being used less these days in the US due to CAFE standards and the move to 5w-20 oils in newer autos. However, our bikes have different needs than a CAFE controlled engine.

 

Want to learn something about oil? Go Bob is the Oil Guy. You will learn more about oil than you can imagine.

 

James

[RFW]

Moly has been around for a long time. It is found, at least in small concentrations, in most all auto oils although it is being used less these days in the US due to CAFE standards and the move to 5w-20 oils in newer autos. However, our bikes have different needs than a CAFE controlled engine.

 

Want to learn something about oil? Go Bob is the Oil Guy. You will learn more about oil than you can imagine.

A couple of interesting extracts from the article....

 

"Engineers and scientists have tried for years to use Moly in motor oils but they have been unsuccessful because they could not find a way to keep Moly in suspension. Once Moly was put into suspension it would gradually settle out. It was easy to see it come out of suspension because a black sludge would collect on the bottom of the oil containers. In engines it would settle to the bottom of the crankcase or clog oil pathways and filters."

 

...and...

 

"Engineers have overcome these obstacles. They have developed a process that keeps Moly in suspension and isn't filtered out. "

 

This post was started by a question about why there was all this "black stuff" at the bottom of the oil container.

 

This implies that the MoS2-additive in the BMW oil in question, is of the "old" type (see the first quote above) that "would settle to the bottom of the crankcase or clog oil pathways and filters".

 

Not a good sign!

 

Bob.

[Joe Frickin' Friday]

Gears do NOT have clearances. Gear teeth are in hard metal to metal contact. The reason they do not wear is because they use an involute tooth form that results in zero sliding contact. Gear teeth ROLL against each other...Because spur gear teeth do not slide against each other, a solid lubricant like MoS2 is useless as a wear or friction preventer, because there is no sliding friction in the first place. This is a fundamental mechanical engineering concept.

 

This is incorrect. In spur/helical gears, pure rolling contact exists only at the pitch point (where the two meshing gears' theoretical pitch circles make contact); this is a brief instant during the period of time when two gear teeth are in contact, and for the remainder of that period, the motion is in fact a blend of rolling and sliding contact.

 

Where Hertzian contact stresses exist (as in cam lobes, ball/roller bearings and meshing gears), a measure of protection is offered by the fact that oil undergoes a tremendous increase in viscosity when subjected to the high pressures in those tiny contact zones. One reference compares the change in viscosity inside and outside the contact zone of a ball bearing unit as being equivalent to the difference between cold asphalt and light sewing machine oil. Where this is still inadequate to the task (very high loads and/or low speeds, the latter leading to long contact times), EP additives like moly and ZDDP may help.

[RFW]

This is incorrect. In spur/helical gears, pure rolling contact exists only at the pitch point (where the two meshing gears' theoretical pitch circles make contact); this is a brief instant during the period of time when two gear teeth are in contact, and for the remainder of that period, the motion is in fact a blend of rolling and sliding contact.

While I am no expert in the detailed design of gearteeth, I spent about a month on the subject in my Machine Design course in Engineering school. There, a great deal of stress was made on the "fact" (at least it was stated emphatically as such) that standard spur gears (straight cut or helical cut) use an involute tooth form over the entire tooth face except in the case of undercut gears (extreme numeric gear ratios). By definition this results in rolling contact over the entire tooth face.

 

So unless gear design principles have changed, I'd have to disagree with your assement.

 

Bob.

[Joe Frickin' Friday]

While I am no expert in the detailed design of gearteeth, I spent about a month on the subject in my Machine Design course in Engineering school. There, a great deal of stress was made on the "fact" (at least it was stated emphatically as such) that standard spur gears (straight cut or helical cut) use an involute tooth form over the entire tooth face except in the case of undercut gears (extreme numeric gear ratios). By definition this results in rolling contact over the entire tooth face.

 

So unless gear design principles have changed, I'd have to disagree with your assement.

 

It is indeed a fact that standard spur gears use an involute tooth profile. But pure rolling contact is not a defining feature of involute teeth (or any other conjugate-action tooth profile system). FWIW, my previous post was a paraphrase from this book.

 

In fact, if you study this animation, and think about the relative motion of the two gear teeth involved, you'll see it's not physically possible to have two gear teeth mesh at constant angular velocity without some sort of sliding contact, no matter the tooth profile.