Synthetics and VI improvers

GW

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VI improvers are added to improve the viscosity index of an oil - synthetic oils have a high natural viscosity index and therefore require very little help in the way of VI improvers. As an example, Amsoil has a natural gas formulation that is a straight grade 40 with a high enough VI index to allow it to behave (and to be called) a 20W40. I am sure there are many other examples of this out there, but this is the only one that I am sure of. Now, as I have found out, some blenders of synthetic oils still do use some VI improvers even in cases where they wouldn't really need to. It would seem that these improvers do have a place - maybe some of the more qualified here can answer to this. Redline has a line of race oils that they say are straight grades (that behave like multi's) but when I called them they did admit that some VI improvers are used. (?) I was told that in the early days, some Amsoil formulations (10W30, 10W40) contained no VI improvers and that now they do use them in these same products. Why? They tell me it is to improve the film strength. Again, I would really appreciate hearing from others on this. [ June 29, 2002, 10:54 AM: Message edited by: GW ]
 

MolaKule

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From GW, "I was told that in the early days, some Amsoil formulations (10W30, 10W40) contained no VI improvers and that now they do use them in these same products. Why? They tell me it is to improve the film strength. Again, I would really appreciate hearing from others on this." There is a class of fluids used in additives called, "multifunctional" fluids which means they perform more than one function. Some of the VII's used do improve film strength as well. Tricresyl or diaryl phosphate is one of those addivtives.
 
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