Need Help The manual states the level should be 152 mm from top of the upper tube. The black box upgrade states 115mm from the top of the upper tube???? Any buddy know which is correct? And yes the Black Box upgrade has been done. Boxxer Manual Pour oil into thr upper tubes while cycling the lower fork legs up and down. With the fork leg compressed with out springs, the oil level should be 152mm from the top of the upper tube. Important: Do not set oil level above or below this specification Black Box PDF 16. Using an oil-height tool, set the oil height to 115mm from the top of the upper tube to the top of the oil. If you do not have an oil height tool, use a ruler and pour oil from the upper tube until the oil height level is 115mm from the top of the upper tube, to the top of the oil (fig. 16a and 16b). Oil height tools may be purchased at motorcycle shops.