Should you use GT85 on your chain?
It appears that there are several products under this name, a general-purpose solvent/protectant and a dedicated bike chain lube.
Reviews on Amazon are rather mixed... One fellow claims no better than WD-40, others appear to like it.
Chain lubes are always controversial and seldom tested in a rigorous manner.   

WD-40 is essentially a cleaner/solvent and has no  more lubricating ability than say...Kerosene.
The best chain lube I ever tried is sadly not being made any more... Schwinn Factory Wax.

Clean-running, persistent, and according to testing by Bicycling magazine, among the top for wear and abrasion resistance.

To my way of thinking, keeping the chain clean and free of built-up crud and goo is as/more important than what sort of lube used.