I found this to be interesting too: http://www.calsci.com/motorcycleinfo/Oils1.html

Synthetic oils were originally designed for the purpose of having a very pure base oil with excellent properties. By starting from scratch and building up your oil molecules from little pieces, you can pretty much guarantee that every molecule in the oil is just like every other molecule, and therefore the properties are exactly what you designed in, not compromised by impurities from dead cockroach shells or whatever. Synthetics were thus originally a reaction to the relatively poor refining processes available from about 1930 to about 1990. The original synthetics were designed for the Army Air Force in WW II. They simply could not make their high- performance turbo-charged radial engines stay alive on the available motor oils of the time.

One process for making synthetic base oils is to start with a chemical called an olefin, and make new molecules by attaching them to each other in long chains, hence "poly." The primary advantage of Poly-Alpha-Olefin "PAO" base oil is that all the molecules in the base oil are pretty much identical, so it's easy to get the base oil to behave exactly as you like. PAOs are called Group IV base oils.

Until about 2000, these PAO base oils had an enormous advantage over mineral base oils in low temperature performance and in resistance to oxidation, which is critical in keeping the oil from forming acids. However, modern group-III oils can nearly match the performance of PAOs at about half the price. Because of this, PAO based oils are rapidly disappearing. There are new processes being investigated which may significantly cut the cost of producing PAOs, and make them an important component of oil again.

Another type of base oil is made from refined and processed esters and is called Group V. Esters start life as fatty acids in plants and animals, which are then chemically combined into esters, diesters, and polyesters. Your vegetarian girlfriend should love that. Group V base stocks are the most expensive of all to produce. However, the esters are polar molecules and have very significant solvent properties - an ester base oil all by itself will do a very decent job of keeping your engine clean. So, people who are serious about making a superior oil will usually mix some Group V oils into their base stock.

They use alcohol too when making esters. I guess the price of ester-based synthetic oils will go up when the price of the alcohol, acids, and vegetables go up.

 

There are three different types of "synthetics": Rotella is an example of Group III, Mobil 1 and Amzoil are examples of Group IV PAO, and the esters (Redline, some Maxima, Klotz, and Motul) are Group V.

Esters and PAO compliment each other in many ways. The best oils are ester based, with a little PAO thrown in for "balance". I run Redline in most everything, but sometimes Maxima Ultra, Extra, or 530MX in some machines.

 

Screw that... Amsoil locally here is $7.95 a quart... but I run Standard Yama-Lube 20W40... I have always ran OEM MFG oil... whether on my old '90 XR250 or my present quad. With my sleds I always ran the OEM oil as well... always treated me well! I sold my XR in 2003 and it still had the original engine - never rebuilt and still ran pretty good considering!

I bought a Case of 4 - 1 Gallon jugs for a Mear $56 bucks! about $3.50 a quart.. at that time.. I also bought 2 cases, yes 2 cases of Ski-Doo XPS Semi-blend 2 Stroke injector oil for $80 a case ( 3 1-gallon jugs) normally that stuff is $30 a gallon.. and all the Ski-doo stealerships will definitely be raising the prices.. so I bought in before snow flies!