I would like to understand comnoz advice, if any engine that makes foam d/t not long hot enough opperation how would venting too cold mess into too cold oil tank do anything to improve foaming?
Some factoids on oil nowadays to avoid such things in most cases.
9. Engine Oil Must be Non-Foaming
Because of the rapidly moving parts in an engine, oil is constantly being mixed with air. This produces foam which is a lot of air bubbles which may or may not readily collapse. These air bubbles normally rise to the surface and break, but water and other contaminants slow this process.
Foam is not a good conductor of heat, and will impair the cooling of the engine parts. Also, foam does not have the ability to carry much of a load which would result in excessive engine wear.
Foam depressant additives are used in the manufacture of automotive lubricants, to reduce the amount of foaming.
Additives
Detergents are used to perform two key functions. One is to neutralize the acidity byproducts of lubricant oxidation and thermal decomposition and the other is to keep contaminants as sludge of oxidized oil soluble. The total base number (TBN) of the detergent reflects its ability to neutralize acids.
Dispersants control contamination from low temperature operation. Both detergents and dispersants attach themselves to contaminant particles, and hold them in suspension. The suspended particles are so finely divided that they pass harmlessly between mating surfaces and through oil filters. The contamination is removed from the engine when the oil is changed.
Oxidation Inhibitors reduce oxygen attack on the lubricating base oil.
Corrosion Inhibitors protect non-ferrous metals by coating them and forming a barrier between parts and their environment.
Rust Inhibitors protect iron/steel from oxygen attack, by forming a protection screen over the surface of the metals.
Friction modifiers reduce friction by physical adsorption of polar materials on metal surfaces (fatty acids and esters, molybdenum compounds...).
Anti-Wear agents form a protective layer by chemical reaction with the metal surface (normally a metal soap).
Extreme Pressure additive also known as antiseize additive, antiscuffing additive, form a protective layer by chemical reaction with the metal surface, increasing the load at which scuffing or seizure occurs.
Foam Depressants controls the tendency for fouming. Detergent and dispersant additives can facilitate aeration of an oil which results in foaming. This can reduce the lubricating ability of the oil, and interfere with the pumping of the oil.
Viscosity Index (VI) Improvers control the viscosity of multi-grade oils. They are long-chain polymers that function by uncoiling or dissociating at elevated temperatures, increasing the oil's resistance to flow. At low temperatures, they are "tight-balls" which do not significantly increase the oils resistance to flow.
Pour Point Depressants give an oil better low temperature fluidity.
reference:
http://www.mts.net/~dbrad1/index.htm#Reference
http://www.tribology-abc.com
