Additive Interactions and wear protection

[JAG]

http://www3.interscience.wiley.com/cgi-bin/abstract/112469512/ABSTRACT?CRETRY=1&SRETRY=0

Quote:

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Preventing valve train wear in automotive engines is one of the most important properties of an engine oil. However, the influence of engine oil additives on valve train wear has not been sufficiently clarified.
In this investigation, the antiwear performance of additives (such as ashless dispersants, metallic detergents and zinc dithiophosphate - ZDTP) and the influence of the interaction of the additives were evaluated.
Secondly, metallic detergents were considered. An overbased calcium sulphonate and an overbased phenate were found to have good anti-scuffing performance when evaluated in engine tests and in Falex wear tests. However, from the results of four-ball tests, these additives did not appear to have many extreme pressure properties. From surface analyses, it was determined that a calcium carbonate film was formed on the sliding surface of the Falex test piece, and this film provided good protection against wear.
Finally, the interaction of ZDTP, succinimides and calcium detergents and their influence on valve train wear were studied. The decomosition temperature of ZDTP increased with certain additives. including the succinimide. As a result, scuffing was more prone, at temperatures below those increased temperatures. Also, changes in additive concentration on the sliding surface, due to competitive adsorption, altered the antiwear performance of the oil.

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Succinimides are a type of dispersants. What do these results say about effect of certain dispersants on anti-wear performance?

 

[RedOak]

Looks like a high dose of calcium is needed with the dispersants? That is just a unqualified guess. Oils with high doses of calcium do seem to offer good wear protection.

 

[Auto-Union]

This should answer a lot of questions of the home blenders as well as additive junkies. Was it intent to warn away from chamging oil formulations?
This seems like a good article for the "Tech" section.

 

[Auto-Union]

It might directly address the high Fe in Mobil 1 used oil analysis. Does someone know off-hand how/if this applies to the Mobil add pack?

 

[buster]

This article is exactly why creating your own concoction should not be done.

 

[JAG]

My main thoughts from this article are that making a long drain oil requires higher levels of dispersants. If a type of dispersant was used that increased the decomposition temp of ZDDP, some anti-wear protection may be lost...probably more so if engine oftens runs while not up to full temperature.

I think but have no proof that a dispersant molecule that is holding onto a "bad" particle may not interfere with any ZDDP molecules. This could be one reason that wear rates are lower as the oil is in use longer. The dispersants get tied up doing their intended job rather than messing with ZDDP. It's just a guess for now.

 

[JAG]

Auto-Union, I'll post this in the Interesting Articles forum. Let's hope more people who rarely leave this forum read the Technical Forums.

 

[Pablo]

And the reason why Amsoil says (basically) mixing oils won't hurt anything, but don't do an extended drain on the brew.....

 

[deven]

Maxlife has over 3000ppm of calcium. food for thought