Viscosity Index Improvers.....dino vs. syn

[NewGuy]

Does anyone know if VIIs for dino are designed differently than those for synthetics? It would seem that the hydrocracked Grp III and PAO-based synthetics would require a different VII simply because of their low polarity and tightly controlled molecular weights. If these Grp III and IV base stocks require different VIIs....then what types are used? Are these inherently better additives (shear stable)? Do they bring increased solvency for the other additives? I am just curious about the different methods for formulating a synthetic vs. dino lubricant!!

 

[dwendt44]

I'm sure some companies use different VIIs that work best in synthetic oils(i.e. Amsoil) as they don't make a plain dino oil. However, most oil companies use additives and VII improvers than will work/function in all motor oils. It's economical; why stock, store, and use severl adds. that do the same thing when I will do? Remember, all common oil makers adhere to the mixability rule.(by custom or industry standards, etc.). That is, all oils will mix with all other oils. Some even mention that misability in their ads, and web page. I seriously doubt any additives would 'clash' and cause problems.

 

[bruce381]

VII's are somewhat dependent on base stock type and solubility. bruce

 

[TallPaul]

If I understand correctly, ester base oil is it's own VII to a large degree. That may explain why (so I have heard) that most of Redline's multigrades are made without VII added (only the 5w40 I am told has a little VII added). So Redline is both straight weight and multigrade at the same time.

 

[Ray H]

Group III and especially Group IV base stocks both have higher native viscosity indeces, further reducing their dependency on VIIs.