About 15 yrs ago I had several baking pans I used for making bread….some of them were used as dairy pans and some as fleishig. We moved out of town and put our things in storage for over 7 yrs. When we finally got our things, I was not quite sure about some of the baking pans, whether they were dairy or fleishig? they were all made of glass or pyrex. I was sure about some of them that were dairy. But some others I was in doubt about but thought they were fleishig and used them as such. HOwever, I want to know if I should throw them out or can i continue using them as fleishig? Another question I have is concerning a self cleaning oven. This is an oven that was not used for about 3 years. It was fleishig. I self cleaned it and have made it now milchig. however, when I opened the oven after the self cleaning cycle, there was a little bit of dirt still on some parts of the oven near the edge, near the glass window part. I washed off those stains but want to be sure it is ok?
As mentioned in the previous post, Pyrex pans concerning which you have a doubt should be kashered by means of immersion three times in a tub of boiling water. Those who follow Sephardic custom may use them without concern.
Concerning the oven, the self-cleaning feature is sufficient to kasher the oven. If you are concerned with regard to the dirt you found, you can go through the cycle again, though there is no need according to the strict halachah.
Sources: See Magen Avraham (Orach Chaim 509:11), who does not permit the conversion of utensils from meaty to milky and vice versa; however, most authorities do not accept his position, and in any case ex post facto he certainly concedes that the utensils are permitted for use. See also Shach (YD 121:8), and gloss of Rabbi Akiva Eiger, concerning the need for libun – a self-cleaning feature is certainly libun kal, and might even be considered libun chamur.