Hi David,
I agree do what have been said. I mainly use Mr Color levelling thinner and either Tamika, Mr color or (recently)AK Real collars. All eyeball thinned between 50 to 60/50-40, but sometime even thinner. I adapt my thinner to the needle I am using, If I use a 0,2 I go thinner. I try to keep my PSI very low, approx 15