So I have seen a LOT of posts on various forums as to what oil to use in the TR6 Zenith Strombergs, or SUs for that matter. Moss sells SU carb oil, but kind of pricey. The important thing is the 20 wt. After much research decided that I would go with straight 20wt Three in One Oil. The links that helped me decide were http://www.british-cars.net/triumph-tr6-bbs/carb-dashpot-oil-200405030042384442.htm and http://www.buckeyetriumphs.org/technical/Carbs/CarbsI/CarbsI.htm . Home Depot sells it 4 Oz for $3 or 8 Oz for $4.29.
One 4 Oz container was more than enough for both carbs, with plenty left over.