ITD, I am not familiar with SteelFlex but Greg's ground grease is pretty tough and good and slick. I have seen Frog Spit, Greg's mix, and Bobby Jr.'s Predator mix and in my opinion the last two totally blow away frog spit. They both last longer and are slicker. Greg's may be a little cheaper per gallon but don't quote me on that...call Greg and Bobby to see for sure.
Greg's # is (863) 676-5093 or (863) 676-5947
Predator's # is 863-557-0098
You won't be dissappointed with either.
Adam