I don't know anything about pimentos in oil. I''ve never heard of using oil and it's expensive, but for real authentic pimento flavor you can check out my pepper lacto-fermentation article here:

www.paleotechnics.com/articlesindex.html

They can be stored over the winter. The problem with pimentos is finding a variety that will keep it's firm texture and not mush out. Shepards ramshorn has done best for me, it's actually a frying pepper, but makes great red ripe pimentos. Try doing a couple pints of whatever you're growing and see how it turns out.