oil condensation

[porsche930dude]

does condensation in oil burn off and cause no ill effects or does it stay and mix with the oil? Or does it burn off but still break down the oil . Also do plastic tanks condensate like metal ones do? i wouldnt think so

[M.D. Holloway]

Water is a prime reason for deposit formation. Various deposits such as varnish, lacquer, gum and sludge are basically the result of oxidized oil and are all carbon-based materials. These materials are typically large in molecular size compared to other compounds found in lubricants save the base oil. Deposits form by chain polymerizations which require an initiator in the form of a free radical or another reactive specie. Free radicals and reactive species (anions or cations) can be generated by many of the conditions found in engines.

Chain polymerizations occur by the propagation of the reactive molecule by successive additions of large numbers of other reactive molecules. Water as well as particles and certain metals provide a great environment for such a reaction.


Typically, the oil undergoes a transformation from one molecular structure to another. This can be in the form of a mixture of a contaminant such as fuel soot with motor oil. It can also be varnish or lacquer on a piston pump cylinder from excessive temperature and load. More often it is the breaking down of the base oil and the building up of a new compound. This re-constitution develops through a series of steps. The first step is the generation of a reactive compound or free radicals. There are several ways in which these compounds develop. Once in the system, they combine or polymerize into new compounds in the form of deposits. Various environmental conditions can facilitate the generation such as temperature, pressure, water, solvents, acids, caustics and various metals.

Free radicals can develop by a few different methods. One is through mechanical energy such as milling, pressure, and high pressure combined with shearing deformation, or shock waves through a non-thermal process. Another way is from acids that cleave the molecular bonds. A high concentration of short or moderate chain-length molecules of the oil can break creating a higher population of free radicals. These short reactive species readily bond with other like species or contaminants and polymerize into deposits. A long chain-length oil molecule will produce less reactive species due to bond length and restricted molecular mobility. Excessive heat and pressure can also break the molecular bond and form free radicals that in turn will polymerize into deposits.

I actual did some research into this awhile ago. It is interesting. The rate at which the reaction takes place actually accelerates with time (and heat). It would be natural to assume that the reaction rate would slow down with time since the concentrations of reactive molecules and initiators reduce as they are reacting. The exact opposite is true. Three routes also known as diffusion-controlled termination steps explain this behavior. The first route is a translational diffusion of two of the propagating radicals until they are in close proximity to each other. The second route is the segmental diffusion of the polymer chains. In this route, the rearrangement of the two chains occurs so that the two radical ends are close enough to react with each other. The third route is the actual chemical reaction of the two radical ends to form the polymer or in this case the deposit. During the course of the reaction, the translational diffusion route decreases faster than the increase rate of the segmental diffusion route. This is how rapid autoacceleration occurs.

As for which tanks contribute to more condensation? Are you refering to the fuel tank or the oil container? It would have more to do with the seal and the atmosphere that the tank itself - any container designed to hold oil would not allow permeation of moisture.

[stomachmonkey]

I had a way more complicated answer, Mike summed it up very well.

[M.D. Holloway]

Well, after all that - here is a pic of my sort of mechanic!

[DanielDudley]

You want to drive your car until the oil reaches temperatures above the boiling point of water, every time you drive it.

And then you need to give it a good run.

[RWebb]

The boiling point is not required - long enough at a lower temp. will volatilize all the water.

won't hurt tho.

[porsche930dude]

Well.. thanks. It took me a few times to read that and as many days but i think its safe to say you lost me after the first sentence
As for the type of container which condensates more i was refering more twords fuel tanks. Since my jeep and storage containers are all plastic tanks and i usually dont put sta-bil in them

[M.D. Holloway]

There is enough evidence published as well as not that indicates water is not a good thing in any sort of oil lubricated system. Sta-bil is a good choice as an antioxident for your fuel. The dryer and cleaner the oil, the longer you engine will last. Trust me.

[Mule]

My mechanic keeps condensation under control.