I see different weight ratios quoted for the zinc and the phosphorus in the ZDDP on several of these sites. Don't know enough to explain that fact.
Stuff that is sooooo concentrated you can't get the sediment of the bottom of the bottle mebbe might leave some portion of the goodie behind when you poured it out each time. Mebbe.
(zinc is heavier, right?)
Redline has a clear bottle, and it has clear instructions to shake the piss out of the bottle before pouring as some ZDDP does come out of solution even with the big 16 oz of carrier oil.
Good news is -- if you can get it all out of the little bitty bottle and into the gallon Rotella jug, the suspension package in Rotella will likely keep it up in suspension until you need it. I'd shake it up real real good though.
And I'd shake the piss out of it again before pouring out that last 2 quarts after sitting for most of a year ....