Moly added to oil

[redcar2003]

This is my first post, I hope this hasn’t been gone over before!

I am wondering on the effect of Molybdenum Disulfide or Titanium Disulfide on the brass present in motors.

I have been reading a bit on GL 4 and GL 5 gear oils and the difference in sulphur levels affecting gear boxes with brass components.

Is this the same problem with engines, or does frequency or oil change, etc, make a difference.

Thanks in advance.

 

[krismoriah72]

We have a toyota celica with a 5speed tranny. I was getting ready to change the fluid myself until i ran into the GL4 vs GL5 dilemma. Supposedly the GL5 eats the brass wheras the GL4 does not. I believe it has to do with the sulphur.

Regarding the moly issue.. it seems that the trend now is to go away from moly and towards calcium and sodium in engines.

I am curious too..maybe an expert will clarify.

 

[lewdwig]

IIRC the calcium and sodium are from detergents, the moly is for anti-wear.

 

[JHZR2]

Read the lower half of this, at minimum, to get some great insight.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=729289

 

[mechtech2]

It would be hard to find brass/bronze in modern vehicle engines.
Maybe the wrist pin bushings?

 

[redcar2003]

Thanks for the article JHZR2.

It explains a lot! Even thought it applies manly to gear oil it seems to suggest the sulphur parts of moly additives are non reactive.

I have started adding half a tin of Liqui Moly (correct spelling) at my oil changes and have seen much less iron on my magnet since then. I wanted to check though, as it seemed pointless to spend the extra money saving iron if I only had to rebuild early anyway due to bearing failure.

That seems to answer my question, but please add if you have more info - I'm a glutton for punishment!!