Where do the additives go ?

[Shannow]

Seen a couple of UOAs where people refer to additives "depleting", evidenced by a reduction in element x, y and/or z.

Where do they go ?

Do they form compounds that stay in the filter ?

Drop out as sludge ?

Volatise and run out the PCV ?

Plate out on parts ?

Or tests to test lab variance ?

 

[pitzel]

Just get neutralized and convert to other things often.

For example, calcium bicarbonate (a TBN enhancer) and sulfuric acid (a combustion gas acid) combine into calcium sulfate and carbon dioxide, the former dissolving in the motor oil, the latter coming out of solution and into the PCV system and ultimately into the atmosphere along with the rest of the CO2 that is produced from the burning of fossil fuels.

Some additives are volatile, for example, zinc dialkyldithiophosphate, which is apparently volatile enough to be of concern to cat converters and certain combustion gas path instruments.

[ March 04, 2005, 03:44 AM: Message edited by: pitzel ]

 

[Shannow]

pitzel, yep, I get that bit...but the elemental calcium dissolved in the oil should not change through the process of chemical reaction.

 

[pitzel]

quote:

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Originally posted by Shannow:
pitzel, yep, I get that bit...but the elemental calcium dissolved in the oil should not change through the process of chemical reaction.

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If I remember back to college chemistry correctly, sulfates like to precipitate out of solution into insolubles in non-polar liquids.

The role of detergents is to enhance the solubility of the byproducts, but detergents do not provide for perfect solubility.

A more complete answer to your original question would be, 'all of the above'.

[ March 04, 2005, 04:02 AM: Message edited by: pitzel ]