MoS2 Additives

john clarke johnclarke303 at
Sat Mar 16 11:48:11 EST 2002

My car is 12 years old, other than oil changes, a couple of flushes and new 
spark plugs, nothing has been to to the "innards" of the engine (timing belt 
is an "outie", pardon the pun).  I have been pretty religious with the oil 
changes but there was a couple of times I probably pushed it past 5000km.  
It doesn't burn any oil (or at least enough to be noticed) even when I run 
with a synthetic 0W30 in the depths of winter (can get down to -35C here for 
a month or two).  Regardless, there is undoubtedly some wear on the cylinder 

The active ingredient in these additives is the mineral molybdenite (MoS2).  
Not to be confused with molybdenum, the metal which is commonly alloyed with 
chromium (Cr) to form lightweight, high tensile steel--commonly used in bike 
frames and really pioneered by the Germans for use as barrel liners in the 
Big Bertha railway cannons.  The name molybdenite is derived from the Greek 
"molybdos" for lead.  Molybdenite in its' natural form is a bluish, 
lead-grey metallic sulphide mineral that has a layered crystal structure and 
is very soft.  It generally forms aggregates of flexible laminae that you 
can break along crystallographic planes in your fingers (will smear like 
soft graphite and leave your fingers greyish-black) ie. it feels very 
slippery.  It is thermally stable up to about 1675C.

These properties seem to make sense that it can, theoretically,  act as a 
material, when added to engine oil, that can "smear" along cylinder walls to 
fill any small scratches or grooves worn in over time.  I have no 
disallusionment that it can improve upon the lubricating properties of dino 
or synth oil (unless your engine is a day older than God and the oil hasn't 
been changed since).  I guess I'm curious if it will act like it should, 
THEORETICALLY, or will it react with the oil, moisture, blow-by combustion 
gases etc. to form a sludge and gum up oil passages etc (molybdenite is 
non-magnetic and semiconductive).  The typical crystallographic thickness of 
molybdenite, across the sheet structure, is in the order of 3.16 Angstroms.  
Maybe you would need to add an inordinate amount to make any difference 

I would just like to know if anyone has any knowledge of the effects of this 
stuff in a modern engine.  Why?  Because just maybe it can help reverse, or 
slow down cylinder wall wear.  Most people on this list seem to have cars 
that are 8-15 years old and are interested in preserving them and minimizing 
maintenance.  I don't care if you change your oil every day, you still get 
wear on anything that isn't submersed in oil every time you cold start the 
engine.  Intuitively, (to me anyway) an additive with MoS2 has the potential 
to perform as advertised on the can (w.r.t. reducing scratches) --has 
anybody done a before and after comparison? Simple.


>From: Kneale Brownson <knotnook at>
>To: "john clarke" <johnclarke303 at>,quattro at
>Subject: Re: MoS2 Additives
>Date: Fri, 15 Mar 2002 16:05:19 -0500
>One word: Why?
>At 05:15 PM 03/15/2002 -03-30, john clarke wrote:
>>The garage next door has the Canadian equivalent? of LubroMoly or sale for
>>$4.99 a can (half price).  The stuff is called MolySlip and claims not to
>>gum up oil passages, safe for synthetic oils etc. etc.  I am normally
>>weary of oil additives but LubroMoly seems to have a good reputation.  Any
>>BTDT's, WOW, warnings etc. on MolySlip or any molybdenum disulphide
>>additives including frequency of use etc?
>>'90 90q20v
>>Let's leave ProLong etc. out of this :-)
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