[ansarigf]

Time to put some of my Edjumacation to use!

The best oil to use after a little research seems to be mineral oil. Why? Use Google.com and search for chemistry of oils and such.

Organic oils such as olive oils will oxidize over time, causeing it to "solidify" and produce a hard protective coating. This is disasterous wrt a shinai!

Mineral oils (or baby oil) do not oxidize, and hence will remain an oil.

Now, don't worry an awful lot about using olive oil and ruining your shinai. kinetically, the oxidation of the olive oil is fairly slow. Meaning, if you clean and oil your shinai regularly, you'll eand up "washing" away the oxidized bits and replacing them with fresh oil. (like disolves like).

Next, vegetable oils are fairly heavy. if you really soak your shinai in these they will become quite a bit heavier. Most of the oil will be in the outer portion of the shinai, as it takes time for heavy oils to diffuse through the bamboo pores into the core of the shinai, leaving the staves unprotected to "inner fractures".

I'm no expert, and this is just some info i've collected. Its up to you to find your "secret recipe". Whatever the outcome, any oil would be better than none!

Steve.