Molybdenum in oil?

[Spetz]

I remember some years back Molybdenum was highly regarded in reducing friction.

I've then heard that Molybdenum is actually horrible and has been banned in aerospace engines and should never be used.

What is the general consensus about Molybdenum here?

 

[pbm]

I like a healthy dose of it in my oil.....

 

[snowflake]

I haven't seen any credited study that says that Moly is bad, do you happen to have a link?

 

[spasm3]

Never heard this, only the question of it helps. Many oils have some form of moly there as antifriction.

 

[Spetz]

No link, it was more just hearsay etc

 

[snowflake]

I'd imagine that is all it is then.

Although I'm no chemical engineer and its unscientific, my trucks seems to burn less of the oils that contain moly in large quantities versus oils without in the same grade.

 

[Darwin1138]

The reality is that any metallic additive, and by metallic we are referring as anything that is not carbon or hydrogen, will reduce the efficiency and the useful life of the catalytic converter. The newest oil specifications reduce the content of these additives to extend the life and efficiency of the converter but without sacrificing engine life.

About what in the aerospace industry are you referring to? I doubt that the ISS needs any lubrication at all.

 

[TiredTrucker]

Go read the articles at the BITOG home page.

Schaeffer, the oil brand I use for both personal and commercial vehicles, is probably the one brand that really promotes using moly in a big way, even though moly is also in other oils. If there is a problem with moly, my engines didn't get the memo.

 

[CentAmDL650]

The anti-wear additives banned from piston-powered aircraft are zinc and phosphorous. There is some claim that deposits in the combustion chambers of motors which contained Zn & P had a higher probability of causing preignition and detonation, which could lead to a disasterous loss of power for engines at full load like those trying to climb out of short runways.

The main knock on moly as a motor oil additive comes from diesels running DPF filters in the exhaust, as ash formed which carries it then is blown through the exhaust where it tends to clog the particulate trap in an inordinately fast time. So HDEO diesel oils will have a relatively high level of Zn & P but low if any Mo.

 

[pbm]

The reality is that any metallic additive, and by metallic we are referring as anything that is not carbon or hydrogen, will reduce the efficiency and the useful life of the catalytic converter.

Is this still true if the car doesn't burn (use) oil?

 

[Gokhan]

Moly is a great three-in-one antiwear/extreme-pressure/friction-modifier additive and it does no harm. Today it's also widely used in HDEO, as lower Mo ppms in new types of moly -- such as trinuclear moly -- are as effective as the old types of moly requiring high Mo ppm. 100 ppm Mo of moly additive will not contribute to the sulphated ash much.

 

[Realtech214]

PYB has lots o moly and its probably bitogs "Smoothest" oil. I hope this dosnt start a war

 

[KCJeep]

The Jeep 4.0 loves moly I can tell you that. The two "best" UOA's I've ever seen for the 4.0 were both on oils very high in moly.

 

[Clevy]

Years ago I read on an amsoil website that moly was very bad,and their products didn't contain any.
Then suddenly there oils have it in them.
I think at one time the types of moly that were available weren't very good and left deposits on rings and ate bearings. Cummins had something about the potential bearing issue I read years ago however I think today the tech has advanced enough and the moly used doesn't have the same weaknesses as prior types.
I read stuff about mos2 written years ago about it being a solid and the particle size was too big to be of any benefit in an engine however the mos2 available in products like liqui-moly are micron sized and smaller which makes them actually useable,since they can anneal the ridges and valleys on metal surfaces because of their small size,whereas before when the particle sizes were larger they just slid across the metal surface.
Just my theory on the matter. I truly cannot say for sure. I'm a carpenter,not a tribologist.

 

[Shannow]

Molybdenum is an element, and what compound it's in makes a heap of difference.

Molybdenum Disulfide is, I believe the item that Cummins was worried about with their lifters. I can see it not being spaceworthy IN a lubricant, although NASA apparelty allow it on threads.

The "soluble" moly is another kettle of fish, completely different

 

[Indydriver]

This is a bit of a moot point since the SM version is no longer available but I had a bit of a stash of TGMO 0W-20 SM. I decided to save it and use it in my daughters VCM Accord since Honda has used moly to help cure it's well documented problems with this engine.

I tested the FF just to try to see what they were doing in terms of moly loading at the factory. They impregnate the piston skirts so that the moly gradually dissolves into the oil over the life of the fill. This is why Honda and all their dealer's insist on not changing out the FF early. Anyway, we followed their advice to a T in case we had any problems. The MM called for a first OCI at 6300 miles. It tested to 359 moly and had a TBN of 2.0 after that exposure. As expected, highly loaded with metals although the 256 of CU still gagged me a bit.

To make sure I was right on with Honda, I refilled with Honda Genuine Full Syn. The MM called for a change at 6400 miles. This SN oil tested to a more typical 117 of moly and was right there with the FF on TBN at 2.0. Metals were trending down nicely so I didn't check the second round of HGFS. So I decided time to pull out the TGMO SM to give this engine a boost. Just got the UOA back and the results are impressive.

First, I had her run the MM all the way down which meant 7,950 miles, so 1500 or so more than the Honda oil. The TGMO tested to 503 of moly and had TBN of 2.6, 30% more after 25% more miles! Impressive. This is why TGMO got such a stellar rep.

 

[Gokhan]

SM version of TGMO 0W-20 used older types of moly, which required more than 500 ppm Mo. SN version uses the far more potent trinuclear moly, which is sufficient at around 100 ppm.

I don't think they coat the sliding parts in new Toyota engines with anything other than oil these days but I may be wrong.

TBN alone is not an indication of oil performance. TAN is more important. Trinuclear moly is said to have an antioxidant sulfur core that helps reduce oil oxidization, which produces acids. Of course, oil oxidization mostly depends on the base-oil quality.

 

[Shannow]

Originally Posted By: Gokhan
SN version uses the far more potent trinuclear moly, which is sufficient at around 100 ppm.


It DOES use, or people THINK that it uses ?

If there's actual hard evidence for it rather than PPM on a UOA, then it needs to be in the FAQ about the most known about oil on the board...which is pretty scant on facts other than price really.

 

[Darwin1138]

Originally Posted By: pbm
Is this still true if the car doesn't burn (use) oil?

Yes it's true because every car consumes oil, obviously the effects would be different between a car that consumes a quart in 5,000 miles and one that consumes the same quart in 50,000 miles.

But even in an engine with moderate consumption and using oils high on additives, the catalytic converter doesn't die immediately, and maybe you won't need to replace it in the car's lifetime, but the efficiency will decrease, and the car, for example, instead of emitting 10 ppm of NOx, it will emit 50 ppm, which is still a good number, but if you multiply it for 4 million cars in a city, that is a lot of smog that could be prevented.

So, maybe you don't care about the environment, (I know I don't care, specially if people are having children like bunnies) but as I said in my last post, an oil with newer technology, will protect the engine equally well even if it has fewer additives.

 

[KCJeep]

Any indication the soluble moly tends to "build up" or plate surfaces over time, like MoS2 is touted to do? I have noticed continued use of PYB for example might produce better results than just an initial run and UOA.