The devil is in the details. The problem with estimating something like this is you'll find wildly different quality MCT out there. A very low quality, non-pure MCT from China that has vegetable oil added to cut it is probably going to give you a year or two, tops. On the other hand, a very high quality, pharmaceutical, zero peroxide value MCT like mig812 can last an exceptionally long time. I've heard of examples of 4 year old mig812 still testing at 0 peroxide. All storage conditions being optimal (no light, quality stopper, cooler room temps) I'd not be surprised to see mig812 last 10+ years. For a similar pharmaceutical grade ~3 peroxide value Castor oil, I'd imagine 3+ years a real possibility. Freezing anything will dramatically slow oxidation and API degradation, and in turn enhance shelf life, likely to the point of out lasting most of us easily.