Hi Myrna- I color my grays too, so I do get that. One thing I can tell you is this; since I have eliminated glycerin for the summer, my color seems to last longer! I have read that glycerin pulls color out of hair, and didn't pay much attention to it until I noticed it as a side effect of not using glycerin anymore....
I also just wanted to say something about you not using leave-ins anymore- from my understanding with low porosity hair, your rinse out is not really ever absorbed, so moisture that stays ON the hair for longer, is more important. (Per KathyMack)
2C/ Coarse/ Normal porosity/ SW Florida/ Salt & Pepper
Cleanse: CJ Daily Fix, JC Cleansing Cream, TJ Tea Tree Condish
Condish: JC Too Shea, CJ Curl Rehab (both as RO & LI)
Stylers: UFD CM, CJ PP, JC Spiralicious, Darcy's Cream Gel & Cocoa bean whip