What are the detriments of V. Improvers?

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Why are there a lot of 5-50 different branded oils on the shelves (all synthetic) and only M-1 makes a 15-50? Is this so because Mobil believes in using LESS V. Improvers than the others? Are there detriments to using oils with these? What are they? Why wouldn't one use a 5-50 in cars that recommend 5-40, 15-50 or 20-50?
 
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For the most part, it's the VI improver that shears over time in an oil, which results in the oil dropping in grade, say from 50 to 40 or 30 wt. All things being equal, the bigger the spread between the low temp viscosity and the high temp, the more VI improver needed. Thus a 10w30 oil will require less VI improver than a 5w30 and therefore should be more "shear stable." But with motor oils, all things are rarely "equal" (especially when it comes to synthetics) and that's where it can get confusing. Because of the high natural VI of the PAO and esters used in Mobil 1 oils, what I said above sometimes doesn't apply. For example, there is good (though mostly anecdotal) evidence that Mobil 1 0w30 and 0w40 have LESS VI improver than the 5w30 and 10w30. The wide range in viscosity with these oils is accomplished primarily with the blend of high VI PAOs and esters in the base oil makeup. The 0wXX grades of Mobil 1 are their most advanced formulations. Of the more "traditional" grades of Mobil 1 (5w30, 10w30, and 15w50), one would expect the 10w30 to have the least VI improver, though it could very well be the 15w50. Mobil does claim that its Mobil 1 20w50 motorcycle oil has NO VI improver added. Edit: Please note the date of this post. Oil formulations change and any statements made here may not be true for current formulations of Mobil 1.
 
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Patman

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Someone correct me if I'm wrong but I've always been under the belief that as the VI improvers break down, they create more varnish (or sludge?) inside the engine, plus the addition of more VII means the oil itself is less "slippery" since the VII is not really good at reducing friction. Am I offbase here?
 
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An interesing topic. Would I be correct in saying they have developed new ester type VII's and are double duty in certain group II and Group III oils they also help maintain the correct seal swell being the III's do not have the solvency of the I's Also,when these II's came out companies used group I's to aid in prevention of additive fall out. I now see less of this with certain brands,,have they developed additives specific for group III oils? If so,the days of mixing dinos are over for some brands as far as additive compatibility/clash is concerned it would seem. Off topic but of interest I see there is ongoing development of new type ATF seals for the newer fluids used in todays transmissions. [ January 13, 2003, 05:19 AM: Message edited by: dragboat ]
 

MolaKule

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"have they developed additives specific for group III oils?" They have developed additive packages specifically for group III bases.
 

MolaKule

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BTW, Viscosity Index Improvers are not bad guys; they simply degrade like other chemicals in the additive package and have to be replenshed at oil change time.
 
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Some VII's also function as friction reducers, thus as the VII molecule shears, you also lose Friction Modification
 
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I recall asking Red Line about the aproximate level of VIIs in their oil. Dave Granquist responded that their 5W-40 is their only engine oil that uses ANY VIIs. I like the idea that my engine oil needs no VIIs to maintain its viscosity stability over wide temperature differences.
 
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That be the case with Redline, I ought to give Danny @ Maxima a call, just to see if he would be willing to divulge which of their formulations use them, and what percentages. I do know that being some of the viscosity differentials of some of their products, they would HAVE to use some of them sometimes.
 
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Dad2leia, sounds like a plan. I'm curious as well. RL might contain no VII's, but I haven't see any benefit on that from the UOA's we've seen on here. I take that back, I guess the shear stability would be a plus.
 
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Hmm...Office closed. I guess that they jetted out either very early for lunch (PST), or they jetted out for a L-O-N-G holiday weekend. Guess my answers will have to wait until Tuesday...darn!
 
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I run 10w40 in my F150 4.9L inline six most of the time. 10w40 has about the most VII of any standard multigrade on our shelves here in the US. I have yet to see a reduction in hot oil pressure that would indicate permanent VII collapse. And I should see that if it happens. I get about 42 psi at 2000 hot on 10w40 and a 30 wt (10.5 cSt) gives me around 35 psi. So I am wondering if VII collapse is really all that prevalent as I hear it is?
 
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That's OK TallPaul, right now I have Maxima's Premium 4 petroleum based 10w40 in my Dodge. Pressures are fine, engine sounds great, in fact sounds mighty good since I filled up last time with 30 gallons of B20 bio blend that our fuel stop just switched to. I probably will switch though to their synthetic blend for the winter, as I probably won't change it again 'till next spring! I guess it really does depend on the quality of all components, and not just one unit being focused on. Bruce381 has been stating that fact for a while, yet we continue to pick apart different formulations, viscosities, and brands to see if we ourselves can "blend" a superior to what's in that bottle to start with compilation. Maybe we do this in vain, but it sure is fun to play and ponder...:)
 
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guess it really does depend on the quality of all components, and not just one unit being focused on. Bruce381 has been stating that fact for a while, yet we continue to pick apart different formulations, viscosities, and brands to see if we ourselves can "blend" a superior to what's in that bottle to start with compilation.
so true, so true....
 
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WHat about temporary shearing, where in a point of extreme pressure/friction the VII molecules shear, spread out like greased up gummi worms in a woodchipper, is this where additional wear occurs? Viscosity alone doesnt guarantee protection, does it?
 
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WHat about temporary shearing, where in a point of extreme pressure/friction the VII molecules shear, spread out like greased up gummi worms in a woodchipper, is this where additional wear occurs?
Bingo. That's exactly what happens. The "shear" is momentary and a product of how the VI improver molecules align when they are being "squeezed" in the bearing. It's at that point that I call a 10w40 a "phantom 40 weight" because what the bearing is seeing is mainly the 5 cSt or 6 cSt vis of the base oil. That's why an advanced AW/EP additive package is needed in multi-grades, especially the 0wXX and 5wXX grades. It's also why you are typically going to see elevated wear metals in an engine with severe fuel dilution issues that's using an oil loaded with VI improvers. Where permanent viscosity loss due to shear comes in is when the VI improver molecules are literally torn apart by the shearing action.
 
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Just remember though, this doesn't always mean an oil with more VII's will be less effective than say an oil with none in all applications. You could have an oil with no VII's that is using a lousy additive package etc. I hate to go back to RL again, but I haven't seen proof that it shows lower wear in fuel dilution cases than any other oil. Always exceptions to the rule.
 
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