What oak beans from Stavin did you get? There is Hungarian, light, medium, heavy toast; French lt, med., heavy. and American oak, same thing. Then there is American un-charred, which is just natural splinters, pieces and small chunks of natural white oak. They are all different and will produce different results. You want oak taste, American White Oak un-toasted is what you are looking for.
Also what was the rate? 2 oz and 2.5 oz for what volume? Also you said " If a wine was all grapes, it didn't take on any flavor after 3 months @ 2.5oz. 3 wines that were just juice started smelling like a rubbery/campfire after 2 months." I'm confused. Wine is wine and never juice. It is either fermented to make alcohol, or it is not.
That "burnt rubber" is a sign of sulfur and yeast breakdown and creating hydrogen sulfide. A clean pre 1980 penny in a gallon of wine JUST after fermentation, can do wonders to bind up mercaptans produced during the fermentation, and sitting on lees. Don't leave it it too long. A couple of days and the rack of. At a winery we use specific amounts of 10% Copper Sulfate solution to accomplish this. Usually at the rate of 0..2 ppm for whites up to 0.4ppm for reds. That is not much on a 100 gallon batch of wine. But it prevents off odors, such as "burnt rubber" from becoming pronounced during ageing and bottling. That odor is not from the oak cubes, it is from a wine that has reductive properties, and believe it or not, not enough oxygen during racking. BUT remember, the oxidation during racking is to clear and allow just the right amount of O2 into the wine to counter the addtion of KMBS Potassium MetaBiSulfite. aka campden tablets, or ground up KMBS.
