Does this color mean bad?

The one I see used right regularly turns green The fact that it changed means something I would think that would be correct how much of a change I don't know the chemical manufacturer in the process on the instructions should maybe give you some clue to that. I think the real fact is is that all internal combustion engines with head gaskets and coolant and all that stuff in them are allowed to have some crossover leakage It's very low and I'm sure these test kits are well above those low readings to rule them out. So the fact that it's changing is trying to tell you something maybe the manufacturer's website goes into this in long drawn-out paragraphs for you to read I haven't looked and I don't know the kit you're using and I don't think that's heavily important but they're literature I'm sure is. Just as leak down tests similar issues certain amount of leak down is inevitable. So the tests are made so that when the parameters aren't met you are well above the threshold that you should be above and therefore you get the readings you get back in the old days you didn't get these nice tests You had to look at a bunch of gauges and pump up a cylinder and watch it for a certain amount of time and record numbers and etc etc there was a lot of room for human error. They've tried to eliminate a lot of that and rightfully so You don't want to have to pay scientists to run tests on simple equipment.