Oil Leak

I have installed an oil pressure gauge and the oil sender unit leaks oil around the threads so what is a good sealent that will work permantly. I used threadlocker the red one and after a few months it starts to leak again. I just put permatex 1 on it and I am still waiting for it to complete dry but I dont know if it will work. I have tried teflon tape, teflon paste, threadlocker, permartex 2 and know permatex 1. So does any one know a product that will work for sure.

Are you sure they're the right threads? If you've tried all that stuff and it still leaks, sealant is not your problem.