Why? In the lengths we deal with, RG58B or C is adequate in both attenuation and temperature specs. I'd avoid RG58A (foam insulated) because of its lower temperature rating.
RG316 isn't a good one in any case. Although it is Teflon, it is some what smaller in size thus difficult to attach a connector to, the wire is copper coated steel, and its attenuation is triple that of RG58.
If you know where to go, you can buy RG58 "sized" coax that is silver plated real copper wire, and full Teflon construction. It isn't for the feint of heart, however, as it costs almost $5 a foot!
Alan, KØBG
www.k0bg.com