So is 5w30 too thin to protect ??
5w30 is thicker than 10w30
- Thread starter bdcardinal
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Originally Posted By: skellyman
Originally Posted By: dave1251
Well my theory on this is due to stay in grade requirements a 5W30 needs to be thicker to counter shearing due to the increased use of VII's. So the best I can help you is that yes 5W30's tend to be thicker until shearing overcomes additional viscosity. Once this happens a 5W30 is significantly thinner than a typical 10W30 often a grade thinner. Hope this helps.
Since when do Viscosity index improvers cause shearing?
As others have more correctly answered already on behalf.
Thanks guys.
The long chain molecules in VI Improvers are prone to shearing with use which reduces their ability to prevent the oil from losing viscosity. This shearing occurs when
shear stress ruptures the long chain molecules and converts them to shorter molecules. The shorter molecules offer less resistance to flow and their ability to maintain viscosity is reduced.
This was a selling point for many companies for consumers to use synthetic oils because group IV and V base oils required less VII's to meet multi-grade requirements because higher grade basestocks have a tendency to contain higher VI's. The selling point was since less VII's were used in synthetics, engines that used synthetics would be cleaner because when VII's shear often deposits are left behind.
Originally Posted By: dave1251
Well my theory on this is due to stay in grade requirements a 5W30 needs to be thicker to counter shearing due to the increased use of VII's. So the best I can help you is that yes 5W30's tend to be thicker until shearing overcomes additional viscosity. Once this happens a 5W30 is significantly thinner than a typical 10W30 often a grade thinner. Hope this helps.
Since when do Viscosity index improvers cause shearing?
As others have more correctly answered already on behalf.
Thanks guys.
The long chain molecules in VI Improvers are prone to shearing with use which reduces their ability to prevent the oil from losing viscosity. This shearing occurs when
shear stress ruptures the long chain molecules and converts them to shorter molecules. The shorter molecules offer less resistance to flow and their ability to maintain viscosity is reduced.
This was a selling point for many companies for consumers to use synthetic oils because group IV and V base oils required less VII's to meet multi-grade requirements because higher grade basestocks have a tendency to contain higher VI's. The selling point was since less VII's were used in synthetics, engines that used synthetics would be cleaner because when VII's shear often deposits are left behind.
Originally Posted By: tinmanSC
Most people don't understand the SAE grade system. It's confusing and non-intuitive.
Yep. There are 0w-30 and 5w-30 HDEOs that are substantially thicker by HTHS than are many 10w-30 PCMOs out there. Aside from paying attention to HTHS (if it's published), one needs to notice if the oil has an ILSAC rating or not. If the 0w-30, 5w-30, or 10w-30 doesn't have an ILSAC rating, there's probably a reason for it, and viscosity may be on the high end of the scale, along with ZDDP.
Most people don't understand the SAE grade system. It's confusing and non-intuitive.
Yep. There are 0w-30 and 5w-30 HDEOs that are substantially thicker by HTHS than are many 10w-30 PCMOs out there. Aside from paying attention to HTHS (if it's published), one needs to notice if the oil has an ILSAC rating or not. If the 0w-30, 5w-30, or 10w-30 doesn't have an ILSAC rating, there's probably a reason for it, and viscosity may be on the high end of the scale, along with ZDDP.
Shearing means you give him some of your oil.
Originally Posted By: fdcg27
You might have brought in the fact that the 5W-30s always have higher VI than same brand 10W-30s.
That is the single most important difference between a 5W-30 and 10W-30 motor oil; 5W-30s has a higher viscosity index.
Consiquently 5W-30 oils will be lighter at all start-up temp's even on a 100F summer day.
The same main difference applies to typical OTC 5W-20 and 0W-20 oils. 0W-20 oils as a group have higher VIs and therefore are lighter at all start-up temp's.
You might have brought in the fact that the 5W-30s always have higher VI than same brand 10W-30s.
That is the single most important difference between a 5W-30 and 10W-30 motor oil; 5W-30s has a higher viscosity index.
Consiquently 5W-30 oils will be lighter at all start-up temp's even on a 100F summer day.
The same main difference applies to typical OTC 5W-20 and 0W-20 oils. 0W-20 oils as a group have higher VIs and therefore are lighter at all start-up temp's.
Looks like he changed his story on the last post, as (one hopes?) a result of reading the web pages. First he said that the first number was warm and second number was cold. He even specified this with the "W" number being the warm number and that AMSOIL and Valvoline "got it all wrong." It was pretty funny. Oh well, at least it had a good outcome. Grats on spreading the oil knowledge!
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Doesn't saying a 5W-30 starts off thicker than a 10W-30 contradict the basis of what "Motor Oil University" states? Using the example of 75F being a "cooler" temp 5W would flow more than 10W. Does this change using the testing temps of -40F, or something like that?
Originally Posted By: sabresfan
Doesn't saying a 5W-30 starts off thicker than a 10W-30 contradict the basis of what "Motor Oil University" states?
He is referring to a virgin 5W-30 at hot operating temp's before the oil has begun to shear in service, not cold start-up temp's.
Again it is a generalization which has been rendered virtually meaningless since there are so many exceptions amongst 30wt oils.
Doesn't saying a 5W-30 starts off thicker than a 10W-30 contradict the basis of what "Motor Oil University" states?
He is referring to a virgin 5W-30 at hot operating temp's before the oil has begun to shear in service, not cold start-up temp's.
Again it is a generalization which has been rendered virtually meaningless since there are so many exceptions amongst 30wt oils.
Originally Posted By: sabresfan
Pardon the ignorance......does virgin oil refer to oil before the additives?
It just means before use in an engine. As in, virgin oil = straight out of the bottle.
Pardon the ignorance......does virgin oil refer to oil before the additives?
It just means before use in an engine. As in, virgin oil = straight out of the bottle.
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