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Oil Groups Explained

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Group I

Group I oils are the simplest, and usually will not be found in motorcycles.


Group II

Group II oils are refined by processes known as hydro cracking and isomerization. They have fewer impurities than Group I oils. These oils are the typical “dino†oils that are used in our bikes.


Group III

Group III oils are synthetic oils "so to speak". But they are not the type of synthetics that are built up from scratch but modified from dino base stock. They are actually crude oils from the ground that have been refined by a process known as hydroisomerization. HD Syn 3 falls into this category.
Basically it means a combination of processes that remove more unwanted impurities from the crude oil.

Notice above that group III oils are called "synthetic".
It took a lawsuit, and a firm of lawyers, and a bunch of law suits to decide that. The hydroisomerization process actually changes certain molecules around enough to create new molecules. These molecules are pretty uniform in size and shape, just like in “real†synthetic oil. These new molecules are more resistant to oxidation, so they’ll hold up better and last longer than before.


Group IV

Group IV oils are synthetic oils and are man made. These are one of the groups that most people think of when they talk about synthetic oil. The largest parts of these synthetic base stocks are known as “PAOâ€, for polyalphaolefin. This stuff starts with ethylene gas, a molecule with 2 carbon atoms, and builds up to a molecule with 10 carbon atoms. Then three of these 10 carbon molecules are combined to form the actual PAO. Each molecule is exactly like every other molecule. The molecules are long chains, are more stable, flow more readily, better resist heat induced breakdown, don’t thicken as much from high temperatures, better resist oxidation, and don’t “boil†off, than their dino oil base stock cousins.


Group V

Group V oils are ester-based synthetics. They made from diester, polyolestors, polyesters, and complex esters. They are extremely stable under high pressure, and resist heat, often to near 500º F. They are polar molecules, containing an electrical charge that causes them to bond to metal surfaces. These oils are very expensive, and seldom encountered in our motorcycle world because of the price.


Also see these posts about SYN 3 oil...

Synthetic Oils - Harley Davidson Community

Syn 3 MSDS - Harley Davidson Community
 
i have a question for you
i known of guys for years mixing a few onces of marvels mystery oil in with there motor oil it was used mostly in shovel
heads and older machines ,they swear by this stuff .
what about the use of this stuff in evo and newer engines ?
also does the mystery oil fit into one of the catagories you have listed or is it just a additive packed ?
i dont know much about this stuff and figured if any one knew about it, it would be you
also i enjoy reading all your tech tips
 
Thanks for that.

The Marvel oil is an excellent product and I have used it many times. I wouldn't put it in any one of the groups above as it is an additive.
Basically what it is would be a high detergent additive to clean out the oil systems in any motor before an oil change. It can also be added after an oil change but it shouldn't be needed then if it was used before the change.
You can also mix an ounce or so in the gas too which will keep the combustion chambers clean.

Great for freeing up a stick lifter too in cars.
 
You can also mix an ounce or so in the gas too which will keep the combustion chambers clean.

Great for freeing up a stick lifter too in cars.

I'm glad you wrote that, 'cause wile I was reading I was wondering if I could mix in the new bike. I've done it for years on my last bike and several cars and trucks and every motor has lasted for ever. I wasn't sure if I could use it with the fuel injection though, because I wasn't sure how it would affect the injectors. For A bike I would add a cap full or two to the tank after every oil change.
 
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