Just made some Menthol up myself. I used 1 gram of menthol dissolved in 10ml of PG. Then used this as my flavouring at 20% in a juice recipe calculator. Might give you an idea how strong menthol can be.
Using ego,ce5,happy with them,just need flavours I enjoy,sure I'll get there in the end,smoked for 45 years,so vaping has got to be better,only been vaping 9weeks.