For aluminum machining, I'd recommend YG endmills, the 3 flute variety with high helix. These also have a polished flute for better chip evacuation. They are typically uncoated and will last for a long time. I would not plunge cut with these tools, they like gentle ramp entries.
That said, a wee bit of lube is a minimum requirement for machining aluminum, because you can clog up any endmill when it gets hot, and the aluminum starts to stick to it. A Trico Microdrop system works decently well, much better than nothing. It might result in some smoke generation if you are pushing hard. The small air blast that works with the Trico system also does a decent job of moving the chips out of the cutting zone.
For 316 stainless, I don't have much experience with heavy hogouts, but it can be machined dry with more standard endmill configurations. The high helix endmills for aluminum, while they would cut stainless for a few moments, you'd probably lose the corners of the tips pretty quick, because they are delicate. The correct coating on the endmill is mandatory for stainless cutting, as it needs to be resistant to chip welding.
When you get your coolant system on the machine, flood coolant and HSS or cobalt bearing HSS endmills, in very sharp condition, can do a good job of heavy material removal. Built up edge is less harmful to HSS tooling, so a sharp edge can be maintained for quite a while without degradation like a crumbling of the edge of carbide. But HSS must positively be flood cooled to last very long. The heat transfer rate of stainless is very slow, and so the heat in the cut zone is exaggerated beyond what one typically expects when machining steels.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)