I use both deep fry and meat thermometers, and I can't seem to regulate them. I adjust them by immersing in boiling water and setting them to 212 degrees. However, if they are just sitting at room temperature, say 75 degrees, the deep fry reads around 100 degrees, and the meat thermometer reads around 60 degrees. How can I trust them to tell me what temperature the oil or meat really is? Should I go with digital units? Are they always accurate?