Molybdenum, is there a downside?

[BobFout]

Geesh guys, that VOA is 5 years old.

The current spec'd flashpoint 232C / 450F

http://www.redlineoil.com/content/files/tech/Motor Oil PDS 5-13.pdf

 

[Jetronic]

Originally Posted By: UltrafanUK


Yes you might be correct as I didn't check the figures. Does anyone know why this oil has such a low FP, or which exact Silicon compound is used as an additive. Both of those features of this Redline oil are very rare, as I've never seen either in a VOA before and they both have the potential for causing some confusion over interpreting UOA results.


I can't be sure, but I would bet it's Dimethylpolysiloxane as an anti foaming agent/surfactant/dispersant.

 

[MolaKule]

Originally Posted By: Jetronic
Originally Posted By: UltrafanUK


Yes you might be correct as I didn't check the figures. Does anyone know why this oil has such a low FP, or which exact Silicon compound is used as an additive. Both of those features of this Redline oil are very rare, as I've never seen either in a VOA before and they both have the potential for causing some confusion over interpreting UOA results.


I can't be sure, but I would bet it's Dimethylpolysiloxane as an anti foaming agent/surfactant/dispersant...

...Deposits form during the Thermo-oxidation Engine Oil Simulation Test, so you're not guaranteed to pass if you have a lot of moly...


Jetronic is correct on both counts.

Redline and most others use a MoDTC (soluble) form of moly, which is not simply a suspension of solid moly particles as the cheaper OTC additive are.

 

[MolaKule]

Originally Posted By: UltrafanUK
Originally Posted By: Olas
Originally Posted By: UltrafanUK


3/ CORROSION, too much Moly can increase corrosion rates (Big issue with older diesels), hence some engines must not use an engine oil with Mo in it. Castrol GTX is a good one for such engines.


Under what circumstances might this happen? Is the Mo in 4 litres of Redline & 1 can of LM mos2 of sufficient concentration to cause harm?


I don't think so, as it was Cummins that warned against the use of oils with Moly in them, as it resulted in actual corrosion related failures:
http://www.cumminsforum.com/forum/436983-post11.html

That issue was caused by the use of cheap forms of Moly, not the real German made McCoy Moly!


The issue was the wrong type of Molybdenum Compound, called Molybdenum di(2-ethylhexyl) phosphorodithioate.

It was found to be a great friction reducer in hydraulic systems, but not in diesel engines.

The current chemistry in commercial engine oils is Molybdenum di-n-butyldithio-carbamate in a BALANCED formulation.

 

[Skid]

I avoid high moly oils. The main disadvantage is that engine cleanliness suffers, so extended OCIs are dicey.

Also see SAE paper 2000-01-3553 (Oil Development for Nascar Racing) in which a moly additive showed increased wear similar to high detergent oils. Basically, moly, detergents, and ZDDP compete with each other. Can't have everything. I don't care about wear very much, but I care about keeping pistons clean.

 

[BobFout]

Originally Posted By: Skid
I avoid high moly oils. The main disadvantage is that engine cleanliness suffers, so extended OCIs are dicey.

Also see SAE paper 2000-01-3553 (Oil Development for Nascar Racing) in which a moly additive showed increased wear similar to high detergent oils. Basically, moly, detergents, and ZDDP compete with each other. Can't have everything. I don't care about wear very much, but I care about keeping pistons clean.



What do you define as high moly? And how do you determine who is using tri-nuclear moly, or some other type, and who isn't? It's getting more and more difficult to find oils that don't have some moly in it.

Is there really a fully formulated engine oil that is going to leave deposits of any significance? Where are all the deposits in engines run with Redline oil for years and years?

I'm off to find a unicorn.

 

[Skid]

Just stating my preferences, Bob. If you want to use a high moly oil (like a few hundred ppm), go ahead. If someone gave me some Redline or Pennzoil YB, I'd still use it (with a shorter OCI than normal).

Edit: The oils I've used lately are European Castrol 0W-30, Rotella T5 10W-30, and M1 HM 10W-30. The T5 doesn't seem to last as long as the other two. I tend to stretch my OCI based on my lubricheck device readings.