Can anyone tell me if Klean Strip lacquer thinner can be used? Or what to look for to see if it can be used?

Used for what?

I'm guessing you are asking about DMT extraction. If so, it is a mixture of many solvents, including methanol. It would dissolve DMT free base, but good water separation is questionable and freeze precipitation will most likely fail.

What do you want to use it for? Here's the data sheet on it. It's a mix of a bunch of stuff, including some undisclosed ingredients.

https://www2.pcad.edu/Facilities...%20lacquer%20thinner.pdf

I'm sorry yes for DMT extraction

Nah. "Specific percentage of composition is being withheld as a trade secret" means that they don't have to disclose the exact proportions of the listed ingredients.

Might be fun to fractionally distill it, but I don't think OP would be asking if they were already confident in doing that.

I've been using this to look up contents by brand. While these aren't exact measurements, it does list the peaks.

Klean Thinner

It's 3rd highest concentrate is N-Heptane, but I'm not sure what methylcyclohexane or toluene is.

Methylcyclohexane is a seven-carbon saturated hydrocarbon like heptane but with one end bent round and joined onto the penultimate carbon of the chain to form a six-membered ring - hence cyclo[ring]-hex[six carbon]-ane[saturated hydrocarbon]. The remaining carbon atom, the methyl group, pokes out from this ring. Toluene is also a seven-carbon hydrocarbon but it is 'aromatic' - which means it contains a ring of alternating double bonds (at least formally). It's like methylcyclohexane minus six hydrogen atoms.

Products containing stuff like toluene or xylene will not be conducive to freeze precipitation. DMT is simply too soluble in them, even at low temperatures.