Salt solubility test

[JAG]

Hello. As some of you know, I have an odd fascination with testing motor oils at home. While thinking about motor oil's polarity (& solubility), I got curious as to whether motor oil could dissolve table salt (NaCl). I only tried it in one oil so far, Lubromoly 0W-40, and just put a few crystals in so I could tell what went on. Well, after over 12 hours and even some heating, it did not apear that any of the salt dissolved. This oil has 70% PAO, some mineral oil for additive carrier oil, and the rest additives. I would not expect PAO to dissolve any of the salt but thought maybe the detergents (which are polar molecules) would dissolve the salt. Does anyone have a chemical explanation for why this did not occur? Thanks.

 

[427Z06]

There's very little of whatever NaCl is dissoluble in. In a running engine, where water is created, presumeable changes the solubility of NaCl in the oil.

http://en.wikipedia.org/wiki/Sodium_chloride#Synthetic_Uses

 

[JAG]

Thanks! That table is interesting. Some of those liquids will dissolve just a tiny amount of NaCl and it seems that virgin motor oil is in the same ballpark. I would need sophisticated equipment to measure the amount so this science project is closed!