I found this on a Mustang board. Relates to AN's in Mobil 1 (Trisynthetic and maybe SS)
[ April 28, 2005, 10:00 PM: Message edited by: buster ]
http://www.corral.net/forums/showthread.php?t=73376&highlight=amsoilquote:
First, I don't believe that the combination of alkaline materials and water would affect the stability or chemical characteristics of an alkylated aromatic. Second, I don't agree that the neutralizing materials in oils are really "alkaline", since alkaline materials can corrode metals just as readily as acidic ones. The neutralizing materials used in oils is generally more on the nature of a "buffer", which has a portion of the molecule which can react with and neutralize the acids formed by combustion, but the remainder of the buffer molecule is not corrosive, e.g. sodium bicarbonate. These materials are referred to as "overbased" materials, but their not really basic (or alkaline) I don't believe.
The alkylated aromatics are probably not used in great volume in the synoils, but most likely only enough to provide solvency for the additive packages. They have a relatively polar group (the aromatic end) and a relatively non-polar group (the alkyl group), which permits them to act essentially like a soap or surfactant, providing a means to make polar materials (many additives) dissolve in the extremely non-polar PAO basestocks. For the same reason, they'll also act as a water scavenger, where the water molecule will attach to the aromatic end.
Lastly, I'd point out that both Porsche and Corvettes come from the factory with Mobil 1. While I wouldn't put it past Chevy to market that as a gimmick, I'd highly doubt that Porsche would do so.
Chemist and former Patent Attorney for Mobil
quote:
The alkylated aromatics used in oil do have high molecular weights, and are produced by reacting an aromatic compound, the simplist of which is benzene, with an activated alkyl group. Usually, the alkyl chain is pretty long, say about 10 carbons or more, and often there are multiple alkyl groups which attach to the aromatic. So the greater the length/number of alkyl chains, the higher the BP.
No, alkylated aromatics are not the only way around the polarity differences between PAO's and the additives. Surfactants are frequently used, which are usually of the structure of a long alkyl chain with a polar group on the end, usually something like a neutralized acid group, eg. R-COO- Na+ (soap). Now the alkylated aromatics are very similar, in that they have both polar and non-polar groups, but the polar aromatic end is not nearly as susceptible to oxidation (turning into an acid) as are the surfactants. Additionally, they have no metals in them, which tend to cause catalytic converter poisoning.
Because the alkylated aromatics have the polar end, when they approach a water molecule, many of the aromatic ends are attracted to and surround the water molecule and hold it in suspension. Surfactants act the same way. If you can picture this, you'll realize that the water molecule is isolated, and the outside of the water/AA globule is surrounded by alkyl groups, which have good lubricity. Is there a limit to their effectiveness in this action? Sure, that's why you need to change the oil.
To answer another question/legend, early in development, Mobil 1 had problems in that the PAO's tended to shrink gasket materials (see the excellent website posted above by Lubrizol, one of the biggest additive package manufacturers in the world--they produce the additive package for Mobil 1). After a year or so, Mobil recognized the problem and fixed it by changing the additive package. It hasn't been a problem for YEARS, yet people remember and word of mouth still has people believing that synthetic oils will cause your car to leak oil.
Main advantages of synoils? VERY low pour point (the point at which the oil starts to flow slowly). Mobil 1 is at about -60C, which means in a really cold winter, your car will start just like normal. Also, because of the lack of the undesirable nitrogen and sulfur compounds in synoils, which are naturally occuring in dino oils and tend to oxidize (form acids) pretty readily at high temps, the synoils, you'll have better high temp stability and form less acids over time.
Now the real deal. Do they really make a difference? Probably not. The dino oils that are out now are so sophisticated, in contrast to those on the market when the synoils came out, you'll never be able to tell the difference. But I still use Mobil 1.
[ April 28, 2005, 10:00 PM: Message edited by: buster ]
