Unusual 75W-90 Cold Specs


Staff member
Jun 5, 2002
Iowegia - USA
Originally Posted by badtlc
So when using Grp III, do you dose/blend the additives like you would conventional, PAO or something else? PAO viscosity characteristics with conventional additive compatibility sounds like a nice evolution.
1) Treatment rate for blending would be the more correct phraseology. 2) When blending additive with base oils we use either a percentage-by-weight or a percentage-by-volume procedure. For example, for the percentage-by-volume procedure, a particular additive package may require a 15% by volume treatment rate. This means 150mL of additive/850mLiter of base oils for 1 Liter, and then you scale it up for the production volume you need. 3) I emphasized "base oils" because in a finished lubricant we may use two or three or more different viscosities of base oils and more than one Group of base oil. 4) some additive packages are for conventional lubricant mixes, some are for synthetic lubricant mixes, some are for both. 5) The additive package for majority Group III and PAO lubricants would have to contain extra solvency chemistry, or you would have to add an ester or an AN to improve solvency. In many cases, a more expensive but effective method is to use an ester-based dispersant. Of course before all of the above is done, one has to calculate viscosities of the base oil mix and additive components, and then once the final mixture is made, make adjustments to tweak the final viscosity and VI. Some additive packages contain the VII, but if they don't you have to add it and then re-adjust the mix for the proper viscosity. So I hope you and others see the complexity in formulating finished lubricants. It ain't as simple as dumping in some additive to a base oil. And when someone tells you that the base oil in a product is Group III, he or she has no clue as to formulating finished lubricant products.
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