Is this true? I know dino oil will emulsify with water if not burned off, and form a emulsion that is bad for bearings.
So does water actually separate in a synthetic oiled engine and will drain off the bottom when you do an oil change.
Water and synthetic oil don't mix much/any better than water and petroluem oil.
If you have water in the crankcase the source needs to be id'd and fixed. If it's "normal" condensation, then you need to "drive" it away.
I think what you may be thinking is:
Synthetic oils don't break down as easily, therefore there are less issues when and if you have water present....
All automotive type engine oil emulsifies with water due to emulsifying agent. However esters tend to be more negatively affected by water. Exactly what this process is I don't know. I assume it absorbs a water molecule and deteriorates its lubricating abilities. This is merely a guess. Someone more knowledgeable in this area will post-hold tight.
Oils can dissolve a small amount of water into their chemistry. The oil analysis book I bought says:
quote:The volume of water the oil will dissove depends upon it's basestock type, basestock condition, additive package, contaminant load and temperature.
New, high-grade, paraffinic basestock absorbs very little. Old, poor-quality basestock with polar additives and lots of contaminants will absorb quite a bit of water. I thought I read that esters can absorb more water than PAO, but I can't find that now.
All oils can emulsify water. That is, water can be churned into globules so small that they won't separate out.
You should never have enough water in a crankcase to pose a bearing problem. If you did, you'd be better off with an emulsion providing much lubrication vs. the first gulp of your oil pump when starting sending a shot of nothing-but-water from the bottom of your oil pan to the bearings.
In any case, it all drains out when you do a change and the water will vaporize away when you drive with the engine oil normally warm.
quite a bit of water. I thought I read that esters can absorb more water than PAO, but I can't find that now.[/QUOTE]
This is primarily due to esters having carboxyl groups, their polar characater (due to Oxygens electronegaivity) will allow solvency for water.
The R-O-R also adds a extra as well, but this part is negligible and it is the carboxyl group that is primarily responsible for this.
from one of my texts, on organic esters:
"Ester lubricants must be hydrolytically stable because they are exposed to humid atmosphere during use and come into contact with appreciable quantities of water in many applications."
The major way to break ester bonds is through thermal decomposition, and with flashpoints of 280 C to 320 C, this is unlikely in normal use.
One of the starting materials for making esters is a very polar carboxylic acid
But after reaction, there remains the acyl group to give polarity
Your facts were right, the naming was just off.
As for dino oils, they commonly have multiple =N-H, =C-OH, -C=O, =S=O, -COOH and other polar groups attached to some of their hydrocarbon skeletons so they're not perfect pure hydrocarbons.