Conflicting information on nonpolar electrolytic capacitor use

[Bartsloty]

This is my first post and I would like to express my gratitude to this forum for providing a wealth of information in the past.

My question is a simple one but the more I read the more confused I get.

CAN YOU USE NONPOLAR ELECTROLYTICS IN PLACE OF POLAR ONES? The following link http://www.bext.com/replace.htm says you can as long as there isn't DC accross the cap but I've also read many posts that say it doesn't matter. Some posts go as far to say that in an ideal world (money and physical space provided) using all nonpolar film caps would be best. Blackgate information indicates that the their nonpolar caps function like a film cap but in a smaller footprint.

I would like to replace the coupling capacitors in my tuner with Blackgate N series but have measured DC across several of these caps.

Any clarification with a detailed explaination would be great! Is my logic off kilter here?

[jcx]

non-polar electrolytics have an oxide film formed on both electrodes capable of withstanding the rated voltage in either direction

for powersupply bypass the non-polar caps have only 1/2 the C for the same size and rating so they aren't often used when a known DC potential is expected but hey will work fine

but non-polar electrolytic caps have less measurable distortion than polar electrolytics - it is best to use non-polar electolytics in all signal coupling applications, even with DC present - unless the even lower distortion film type caps can fit physically or buget-wise