I'm a mobile massage therapist, so if my oils have been in the car and are cold, I ask my client for a small cup of hot water out of the kettle, then put the bottle into that while I am setting up, then it's fab by the time I start. With driving around, my hands are usually a bit cold too, so it warms them up at the same time - double whammy!
I have been known to take a hot water bottle into the car for the journey, to put into my therapy bag to take the chill off my towels/sheets too!
Lesley