The Real Scoop On OIL (From Skip)
#1
08-31-2005, 08:53 PM
The Real Scoop On OIL (From Skip)
Submitted by: Skip (pococj)
Thanks Skip
Here's a bit of a primer on oil in general:
What we call dino oil is simply refined crude oil with an additive package designed to enhance its usefulness for specific purposes. What we call synthetic oil is either built up, molecule-by-molecule, or crude oil refined more than the regular motor oil. Regular oil will consist of various sizes of molecules, generally called short and long chain molecules. Synthetic oil will have all its molecules the same size, and all will be long chain molecules.
There are various types of oils, depending upon their "construction." Groups 1 & 2 are dino oils, Group 3 is the "super-refined" (my term) from crude synthetics, Group 4 is the "pure" synthetics that are built up molecule by molecule, and Group 5 oils are another type of "pure" synthetics.
There are s'posed to be several advantages to the synthetic oils. A couple of the more important include a higher flash point, meaning they shouldn't break down as readily at high temps; better viscosity retention, meaning if you start out with a 50 weight, it'll stay a 50 weight longer; and better resistance to shear, or the chopping up of the molecules into shorter lengths.
Obviously the ability to withstand higher temps before breaking down can be important in an air cooled engine. And staying at that good heavier viscosity for a longer period of time offers better protection for an engine, gear box, etc. Being more shear resistant contributes to the viscosity retention, and might also be of help in maintaining an oil's chemical properties.
As far as the three "holes" in our HDs, the engine will be where the heat resistance comes into play. Also, viscosity retention will be important in order to protect the lubricating properties of the oil, and so protect the engine. And there are gears in the engine that will literally "grind" the molecules apart, so shear resistance is important. Next, the primary doesn't produce that much heat, but the primary chain will be wailing away on the molecules, grinding & cutting the molecules. Additionally, the clutch plates wiil want something that is "smoothly slippery" to help it operate smoothly, but not so slippery that it allows the clutch to slip. The tranny is where the heavy duty gears are grinding and gnashing the molecules into a useless too-thin muck. Once again, the shear resistance is extremely important in the tranny.
A bit here about additive packages: Additive packages are used to give the viscosity spreads, as in 15w-50, 20w-50, 10w-40, etc. The wider the spread the more additives needed to maintain it. But that also usually means the oil will shear down to a lighter viscosity earlier. Makes for a sorta mixed blessing. Of course, you could run a straight 50 or 60 weight, but then you'll do more damage at startup than would happen because the oil sheared down from a 50 to a 40 weight.
Other additives are used to protect the motor from the slow acid buildup occurring in the oil as it breaks down, and still others are used to coat the bare metal with a protective layer in the worst possible case scenario of metal-to-metal contact.
Now for the additive kicker - in every case I researched, except for some synthetics costing about $15 and up a quart (some were over $30 a quart), the additive packages are put in the synthetic base via regular dino oil, at a volume of about 10 - 20%. There might be some less expensive synthetics bases with a synthetic addive package, but I just didn't run across them.
And gear oil ain't "thicker" than regular engine oil, per se. Its viscosity is measured on a different scale, so the numbers make it appear heavier. Take the most common, 75w-90. The 75 part of the gear oil is about equivalent to 10w through the mid-range of 20w motor oil, and the 90 part is equal to a low 40w through 50w motor oil. The 140 part of a 75w-140 gear oil is equal to a 60w motor oil.
Why no
Thanks Skip
Here's a bit of a primer on oil in general:
What we call dino oil is simply refined crude oil with an additive package designed to enhance its usefulness for specific purposes. What we call synthetic oil is either built up, molecule-by-molecule, or crude oil refined more than the regular motor oil. Regular oil will consist of various sizes of molecules, generally called short and long chain molecules. Synthetic oil will have all its molecules the same size, and all will be long chain molecules.
There are various types of oils, depending upon their "construction." Groups 1 & 2 are dino oils, Group 3 is the "super-refined" (my term) from crude synthetics, Group 4 is the "pure" synthetics that are built up molecule by molecule, and Group 5 oils are another type of "pure" synthetics.
There are s'posed to be several advantages to the synthetic oils. A couple of the more important include a higher flash point, meaning they shouldn't break down as readily at high temps; better viscosity retention, meaning if you start out with a 50 weight, it'll stay a 50 weight longer; and better resistance to shear, or the chopping up of the molecules into shorter lengths.
Obviously the ability to withstand higher temps before breaking down can be important in an air cooled engine. And staying at that good heavier viscosity for a longer period of time offers better protection for an engine, gear box, etc. Being more shear resistant contributes to the viscosity retention, and might also be of help in maintaining an oil's chemical properties.
As far as the three "holes" in our HDs, the engine will be where the heat resistance comes into play. Also, viscosity retention will be important in order to protect the lubricating properties of the oil, and so protect the engine. And there are gears in the engine that will literally "grind" the molecules apart, so shear resistance is important. Next, the primary doesn't produce that much heat, but the primary chain will be wailing away on the molecules, grinding & cutting the molecules. Additionally, the clutch plates wiil want something that is "smoothly slippery" to help it operate smoothly, but not so slippery that it allows the clutch to slip. The tranny is where the heavy duty gears are grinding and gnashing the molecules into a useless too-thin muck. Once again, the shear resistance is extremely important in the tranny.
A bit here about additive packages: Additive packages are used to give the viscosity spreads, as in 15w-50, 20w-50, 10w-40, etc. The wider the spread the more additives needed to maintain it. But that also usually means the oil will shear down to a lighter viscosity earlier. Makes for a sorta mixed blessing. Of course, you could run a straight 50 or 60 weight, but then you'll do more damage at startup than would happen because the oil sheared down from a 50 to a 40 weight.
Other additives are used to protect the motor from the slow acid buildup occurring in the oil as it breaks down, and still others are used to coat the bare metal with a protective layer in the worst possible case scenario of metal-to-metal contact.
Now for the additive kicker - in every case I researched, except for some synthetics costing about $15 and up a quart (some were over $30 a quart), the additive packages are put in the synthetic base via regular dino oil, at a volume of about 10 - 20%. There might be some less expensive synthetics bases with a synthetic addive package, but I just didn't run across them.
And gear oil ain't "thicker" than regular engine oil, per se. Its viscosity is measured on a different scale, so the numbers make it appear heavier. Take the most common, 75w-90. The 75 part of the gear oil is about equivalent to 10w through the mid-range of 20w motor oil, and the 90 part is equal to a low 40w through 50w motor oil. The 140 part of a 75w-140 gear oil is equal to a 60w motor oil.
Why no
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