Oil Basics, Part 1
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Oil Basics, Part 1 - 10/19/2005 8:14:55 PM
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pococj
Outstanding HDF Member
Posts: 7259
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From: Texas! Ya mean there''s someplace else?
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This article will try and cover the very basic “stuff” about motor oils, especially as used in our HD motorcycles. Some of it will be technical in nature, but because too much of that junk is only of interest to geeks like me, I’ll try to keep it to a minimum.
Base Stock
The oils we use in our bikes are made up of a base stock and an additive package. The best oils are going to be made of the purest base stock oil with an appropriate additive package to suit the oil’s intended use. What that means is there are too many oils to make life simple, so it’ll help to be at least a little educated about them.
The base stock is plain refined crude oil or synthetic oil. Sometimes the base stock will be made of a blend of refined crude and synthetic oils. In either case, at this point nothing has been added to this base. Generally, the base stock is about 70% of the typical oil product we buy off the shelf. There are several groups of base oils, determined by how they are refined from crude, or how they are synthesized for synthetics. The purer the base stocks, the less impurities that can and will combine with other good and bad molecules, forming undesirable compounds.
Group I
Group I oils are the simplest, and won’t be found in motorcycles. I’ll just say they are made by a solvent refining process.
Group II
Group II oils are refined by processes known as hydrocracking 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. But, they are not the type of synthetics that are built up from scratch, if you will. They are actually good ol’ crude oils from the ground that have been refined by a process known as hydroisomerization. Mouthful of alphabet soup, ain’t it? Basically it means a combination of processes that remove more unwanted impurities from the crude oil.
Notice I said that group III oils are synthetic. It took a lawsuit, a gaggle of lawyers, and a buncha 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 these are one of the groups that most people think of when they talk about synthetic oil. The largest part of these synthetic base stocks are known as “PAO”, 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, and for mumbo-jumbo scientific reasons, 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. I’ve seen some of this stuff for upwards of $32 per quart. However, some of these synthetics are being mixed with Group IV oils and are available at reasonable prices.
Additives
Additives have been around for a long time, but really came into play when the American Petroleum Institute (API) started classifying engine oil as regular, premium, and heavy duty. In the 1950s multigrade oils w
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RE: Oil Basics, Part 1 - 11/29/2005 11:15:03 PM
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2Sixty
Posts: 48
Joined: 7/29/2005
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You might want to check this site out. www.bobistheoilguy.com
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RE: Oil Basics, Part 1 - 11/29/2005 11:16:49 PM
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2Sixty
Posts: 48
Joined: 7/29/2005
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Sorry, I should have read the full post.
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RE: Oil Basics, Part 1 - 11/30/2005 4:16:45 AM
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BikerInTheDesert
Posts: 1007
Joined: 10/29/2005
From: Baghdad, Iraq
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Thanks Skip,
Grand post! Lotta good information, and references!! References are a good thing...
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RE: Oil Basics, Part 1 - 12/3/2006 1:53:31 AM
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britbiker
Posts: 226
Joined: 12/2/2006
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pococj
What a post!! Thanks a million. This told me everything I needed to know regarding oil. I've been scratching my head on this issue for some time. I understood all the words & the way they were arranged!
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