Here is what I would consider to be a good source. Both Rabbi Yochanan and Abaye lacked knowledge of how to treat scurvy on the gums. And they turned to non-Jewish people who told them of the cure. Thus, in Avodah Zarah 28a and elsewhere:
R. Johanan was troubled with scurvy [on his gums] and he went to a certain [heathen] lady who attended to him on the Thursday and the Friday. Said he: What about to morrow? She replied: You will not need [the treatment]. But what if I do need it? he asked. She replied: Swear unto me that you will not reveal [the remedy]. Said he: I swear, to the God of Israel I will not reveal it. She then divulged it to him and on the morrow he referred to it in the course of lecturing. But did he not swear unto her? — He swore: 'To the God of Israel I will not reveal it,' [implying that] I may reveal it to His people Israel. But is this not a profanation of the Name? He mentioned [that proviso] to her originally....What did she apply to it? — Said R. Aha the son of Raba: Leaven-water with olive oil and salt. Mar son of R. Ashi said: Geese-fat smeared with a goose-quill. Said Abaye: I did all this but was not cured, until a certain Arab told me to get seeds of an olive not one third ripe and burn them on a new spade and spread [the ashes] on the gums; which I did and was cured.
Not only that, but Rav Acha bar Rava and Mar bar Rav Ashi argue what that cure was. How could they argue about this metzius? Should they not know it beruach hakodesh? And then it does not even work! This would imply that Chazal can be wrong in science!
If Rabbi Yochanan mystically knew how to treat scurvy on the gums, why did he have to mislead the gentile woman with a false vow? (Though the gemara makes it into a provision she knew before.) But even with all this, why should he have to seek this knowledge from her? He should have known it already! And the same with Abaye, who tried ineffective treatments first. What happened to sod Hashem liyreav?
Furthermore, are you going to grant the Chazon Ish ruach hakodesh to know this sort of stuff but restrict it from Rabbi Yochanan and Abaye?!
I am sure that some of these questions can be answered without too much of a kvetch. But I don't think all of them can. Rather, pashut peshat in this gemara is that Chazal, at times, relied on contemporary science from the gentiles. (I would add, this is a good thing, and an additional reason to should respect Chazal.)