Any oil based rust preventative is just going to be wiped away by your hands every time you use it. It this ratchet is one that you use all the time, you will have to wipe it down with an oil soaked rag after every use.
If the tool is a serious user and you don't want to bother wiping it down every time, take it to your local powder coater. Have them sand blast and powder coat it in a satin or semi gloss color that you like. Doing this will ruin any sort of resale or collector value but it will be very durable and protect the tool for life. There is usually a minimum fee or amount to fire up the oven but a ratchet should cost about $10 once whatever minimum price is met.
I have had several things like antique vices, c-clamps, adjustable wrenches and modern motorcycle parts professionally powder coated and I have always been happy with it. I use the items I had powder coated almost every day and every thing is holding up nicely. The more glossy of a finish you choose, the more durable the finish will be, providing the preparation and application are done correctly. For something like a ratchet, I recommend semi gloss. Full on gloss will probably be too slippery and flat finishes show scratches and wear faster than semi gloss.