Does a person have to wait 6 hours after eating french fries that were deep fried in the same deep fryer as fleishigs? R' Moshe in Iggros discusses vitamins made from liver as to whether you must wait six hours before milk. In the teshuvah he explains that the machlokes between those who hold you must wait even between tavshil shel basar l'tavshil shel gvina is not a machkoles in metzius--everyone agrees that there is no meshichas hataam if there is no actual meat. The machlokes is rather about how far did the rabanan go: was it just meat, or even a tavshil shel basar.... I wanted to know if that would be applicable here as well since the fries are definitely not meant to be a tavshil shel basar?
Answer:
It is permitted to eat milky after eating a pareve dish cooked in a meaty pot.
However, if the oil itself was used for meat (meaning that the oil was not changed before cooking the fries), one must wait after eating the fries.
Sources:
The Tur (Yoreh De'ah 89) writes that one does not have to wait between a meat dish and a dairy dish if neither one contains actual meat or milk. The Bach notes that while Semak allows one to eat cheese after foods cooked in meat fat, the prevailing custom is not to do so, and one should not deviate from the common custom. The Rema (89:3) goes further, saying that one must wait after a meat dish just as if he had actually eaten a piece of meat. Although the Shulchan Aruch is not stringent on this matter, the Beis Yosef (Orach Chaim 173) does mention the stringency, and later authorities (Ashkenazi and Sefardi alike, including the Ben Ish Chai and the Kaf Hachaim) are stringent in this matter.
Eating the fries implies consuming the meaty oil, and therefore one must wait after eating them before milk.
The matter of the Iggros Moshe (Yoreh De'ah 2:26) is not directly relevant to our case, for the pills (made of liver) do not have taste of meat, and there is no concern for the pills leaving residue between one's teeth, so that the reasons for waiting after meat don't apply.