VG is gloopy. Most mixers use PG to thin it. If you don't want to use VG you can use deionized water (pharma grade not car battery stuff) and or vodka. If your VG is non aqueous you can dilute it from between 5 to 20% with no problems if you are going for a 100% VG mix. Havig said that most flavour concentrates are PG based. As an alternative people like cig-eliquid sell their VG as 10% aqueous.