Although a number of people have used red, blue is sufficient. I used blue on mine and it has been in use for several months and several thousand miles now, hasn't loosened up at all. I took the lever off recently to secure the knob with silicone and the bolts were still tight.
Blue will also make later disassembly much easier should it be necessary.
Just be sure that whatever loctite you decide to use, that you use it on ALL the bolts- shifter to trans mounting bolts, lever attaching bolts, and stop bolts. Most of the reported GMM problems have been the result of non-loctited bolts coming loose.