Can't Stop the Squealing!

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I'm on my second lower and even through the 1st one I can not get the dang thing from squealing no matter the feed speed, the bit speed, or how little I take off. it just squeals like crazy. Is it the 4-flute bit or something else. I'm using kerosene as a lubricant/coolant if that matters. I'm pretty sure the lower is 6061 but it could be 7075. It does not do it if I just plunge. BTW, I'm pretty new at milling but have done it for years at work, someone else just set it up and I ran it.