Naflash, Remember, it's the volume within the tank that's important. The volume of the Bimba tanks are all listed for the 1" long tanks. Then it shows how mucj to add for each additional inch in length. Compare the volume of their 1 and 1/16" by 6" tank (about the size of the Too Tech) to a 1.25" or 1.5" diameter tank of a shorter dimension. Find a shorte size that roughly matches the volume of the Too Tech and use that. JohnB's current setup is larger than the Too Tech at about 8 cu. in. total. A larger tank does NOT require more oil. It ALLOWS more. The maximum practical oil level, no matter how big the tank was made, would be limited to how much the compressed fork will hold.