I'm not saying this to be dissagreeable but-there is nothing wrong with teflon tape on tapered pipe threads in hydraulic systems. It's all that I have ever used and by this time, I have put thousands of fittings together without a problem. Case used to recomend either tape or pipe sealant. The trick with the tape is to start 2 threads from the end to eliminate the potential of a piece getting in the system. I would say that if you are the least bit unsure of this, use liquid. If it's 8 PM and the parts store is closed and you need to put a fitting together and don't have liquid don't be afraid of tape.