Bicycle Mechanics - What chain should I use?

I just obtained a 1987 Trek 560EX. It has all its original components which are mostly all Shimano 600. It has the two "Biopace chainrings" that I intend on keeping at least for now. My question is what chain is compatible to this bike? It has its original 6 speed cassette on the original rear wheel.

There are Shimano , KMC and Sram 6 speed chains that will work. Go to your LBS or go on-line. Cost range $10 - $15. You may even look at buying a new cassette for less than $25.

Anything marked as 6, 7, or 8 speed will work.

Anything marked as 6, 7, or 8 speed will work.

+1

The newer chain will work much better than the original, 6-speed width chain. More clearance at the front derailer cage, more-forgiving downshifts, less sensitive to adjustments, and newer chains are almost always quieter.

izumi chains only cheap and the best

3/32 wide , generic ..5,6.7.8, 9 requires the chain be narrower,
till you get tha far the cheaper width will work.

the Sram will last longer than any, the shimano may shift a little better but you may not notice the difference

the Sram will last longer than any, the shimano may shift a little better but you may not notice the difference

My own experience has been that Shimano chain out-wears (out-lasts) every other. I'm including the more modest-level Shimano chains here.
I've also noticed that Shimano chains require less lubing. I assembled a chain from 2 lengths of chain, Shimano HG73 and SRAM PC59, and used it for over a year now. Always it was the SRAM length that started squeeking first. I lubed the entire chain with WL with 30% mineral spirits and 1-2% motor oil.
I replace chains that are approaching 0.5% stretch, but still get several thousand miles of road use, so wear is the minor issue.

Anything marked as 6, 7, or 8 speed will work.

Yep. I'm set on SRAM chains with their Powerlink, which makes for easy chain removal and installation if that's something you care about.

I like SRAM for the powerlinks, though I have also used them on Shimano 8 and 9 speed chains successfully. Really I have not encountered any which are markedly better than others, all seem to work fine. Some people seem to be more sensitive to chain differences than I am.

I assembled a chain from 2 lengths of chain, Shimano HG73 and SRAM PC59, and used it for over a year now.

Dayum!
Now there is an idea!:thumb:
Assemble a chain with Shimano/SRAM/KMC/Campy/Wippermann sections to do a direct comparison of wear.

I like SRAM for the powerlinks, though I have also used them on Shimano 8 and 9 speed chains successfully. Really I have not encountered any which are markedly better than others, all seem to work fine. Some people seem to be more sensitive to chain differences than I am.

Note that SRAM 8-speed Powerlinks don't fit Shimano 8-speed chain, save for two out of the 4 or 5 "IG" model chains.

Powerlinks won't fit any 8-speed "HG" chains, but there are several other brands of link that will.
A heavily-worn Powerlink perhaps might fit on a Shimano HG 8sp chain, and a new Powerlink might fit on a heavily-worn HG 8sp chain, but I mean "heavily" worn! The Shimano inner link is wider.

9-speed Powerlinks seem to work on all 9-speed chains.