Like Darrin said I would go with the quench oil. You can order McMaster-carr 11sec oil for $16 a gal . I use this on my 5160 with great results. You are way better off using oil designed for it purpose .....steve
Due to its popularity I have done testing with peanut oil and have found it to be measurably slower than other vegetable based oils such as canola and others. Peanut oil has a higher flash point and this, I believe, is the reason so many started using it, but the steel doesn't give a rip about flash points, it needs to be cooled. It is more expensive and has slightly more viscosity and the fact that we have adopted tests that are contrary to cutting and edge holding only falsely validates certain quenching practices, i.e. if the knife passes the 90 degree bend test the heat treat must be good, and peanut oil will make a knife that will bend quite well.
All that being said, oil hardening steels can be quite forgiving in the quench mediums you choose. O-1, L6, 5160 or 52100 can probably handle peanut oil just fine in almost any knife thickness, but canola may be cheaper. Here the advantage of a proper quench oil would be consistency and predictability. Organic oils will begin being affected by the hot steel on almost the first quench and will very quickly begin changing in its chemistry and behavior.
While many makers will tell you that they use peanut oil on 10xx series or W series, I would advise against it unless all your pieces are under 1/8" thick. It is what you can't see that really matters in this situation.
As I mention in the plate quenching thread: The logical fallacy of appealing to common practice is one of the most common pitfalls in all of knifemaking. The error of assuming that because a number of people do something that is must be correct should be obvious, but this is not the case on our craft.