Question: What is molybdenum’s real role?

[Bill_W]

ZDDP contains sulfur aswell, doesn't make that an EP additive. It is also heat activated. I, not being a tribologist consider MoS1 first a friction modifier, as I would graphite. Calcium sulfonate on the other hand....

Thanks… Next question. EP additives is on the Stribeck curve. I understand EP is a sacrificial layer. What oil additive does this?
https://www.machinerylubrication.com/Read/30741/lubrication-regimes
Example given would be journal bearings. I know about differential fluid having EP additives.

 

[Jetronic]

none in engine oil, except calcium sulfonate but it's actual role is overbased detergent first

 

[Bill_W]

none in engine oil, except calcium sulfonate but it's actual role is overbased detergent first

That’s what I thought till I saw this.

 

[OVERKILL]

That’s what I thought till I saw this.

EP conditions don't exist in engines, that's why they don't have EP additives. Engine oils depend on AW additives (primarily ZDDP) to control wear. Differentials rely on EP additives.

 

[kschachn]

ZDDP contains sulfur aswell, doesn't make that an EP additive. It is also heat activated. I, not being a tribologist consider MoS1 first a friction modifier, as I would graphite. Calcium sulfonate on the other hand....

Yep, hence the “thio” part of the name.

 

[RDY4WAR]

EP conditions don't exist in engines, that's why they don't have EP additives. Engine oils depend on AW additives (primarily ZDDP) to control wear. Differentials rely on EP additives.

For 99.9% of engines, yes. That 0.1% that are high end race engines with >1" valve lift and >1,000 lbs open spring pressure with .020-.025" lash on solid roller lifters and 9,000+ rpm, EP additives can benefit the valvetrain.

 

[benjy]

a long, read it all but informative post i enjoyed + thanks to all + especially those "in the know"!!!

 

[Bill_W]

EP conditions don't exist in engines, that's why they don't have EP additives. Engine oils depend on AW additives (primarily ZDDP) to control wear. Differentials rely on EP additives.

Thanks for the info. I sometimes interchange EP for anti-wear. Another link to a anti-wear additive used is boron.
https://bobistheoilguy.com/forums/threads/boron-additives.57848/

 

[OVERKILL]

Thanks for the info. I sometimes interchange EP for anti-wear. Another link to a anti-wear additive used is boron.
https://bobistheoilguy.com/forums/threads/boron-additives.57848/

Yup, borated esters are apparently a favourite for Mobil according to Molakule. Boron appears to disappear in service, which is interesting.

 

[RDY4WAR]

The boron is solid particles in a liquid analog of boric acid. Much like dispersants, it can attach to other particles and get caught by the filter. (hence, it depletes in the oil sample) I bet if one was to cut open a filter afterward and analyze the surface of the media, you'd likely find a high saturation of boron.

 

[Bill_W]

So… just cause I am learning am I safe to say anti wear is a function of moly?

 

[OVERKILL]

So… just cause I am learning am I safe to say anti wear is a function of moly?

Yes, moly has some AW benefit, but I'd argue it's secondary to FM. However, it works synergistically with ZDDP, whose role is AW.

 

[Bill_W]

Yes, moly has some AW benefit, but I'd argue it's secondary to FM. However, it works synergistically with ZDDP, whose role is AW.

Thanks again for your input…
https://synlubepros.com/blog/posts/tips/moly-in-engine-oil

 

[spiderbypass]

I know it sounds silly but honestly think people love the sound of the word Moly-

 

[Bill_W]

I think Overdrive’s point that MoDTC and ZDDP are synergistic. That is the sum of both result of a ultimate better product.
Read JAG’s summary post #1
https://bobistheoilguy.com/forums/threads/modtc-effect-on-wear-rates.82100/

ZDDP appears to increase friction, but when MoDTC is added friction is decreased, so it is a friction modifier and an anti wear additive. Working in the boundary zone to reduce wear/friction at startup. MoDTC is turned into MoS2.

 

[Jetronic]

I know it sounds silly but honestly think people love the sound of the word Moly-

Sounds like a rocksong...

Whole lotta Moly
Moly want a crankshaft
Good golly, liquid Moly
ain't nothing but a Moly thing

 

[ZeeOSix]

I think Overdrive’s point that MoDTC and ZDDP are synergistic.

Overdrive's? ... guess he's really kicking it in now.

 

[spiderbypass]

Overdrive's? ... guess he's really kicking it in now.

Again there is something about the word Moly think has some underlying characteristic very slick and synergistic that bitog men just love… no other additive gets an exclamation statement like HOLY MOLY when it is found in larger amounts on a “virgin” oil analysis…

Sounds like a rocksong...

Whole lotta Moly
Moly want a crankshaft
Good golly, liquid Moly
ain't nothing but a Moly thing

Again there is something about the word Moly think has some underlying characteristic very slick, slippery and synergistic that bitog men just love and have undeniable affection for… no other additive gets an exclamation statement like HOLY MOLY!!! when it is found in larger amounts on a “virgin” oil analysis… and I would wager that it has been the most discussed additive on here…. Not even mentioning the actual Liqui Moly additive of Moly aka MOTdc that has been around since the advent of the internal combustion engine…and is still used frequently…

 

[Bill_W]

Overdrive's? ... guess he's really kicking it in now.

Oops? Overkill…

 

[Wizz]

And let us not forget the in depth research/trial article that someone here posted that showed that di moly was more effective than trinuclear moly at preventing wear. This is why Japanese oils prefer the older di moly in high quantities, their research showed it was better at reducing timing chain wear than the trinuclear variety.