>I was trying to very slowly reduce or increase heat of
>the oil in my existing experiments, but many many
>hours later, I still got noticeably inconsistent results.

I think what you are observing is the reason why there is always some sort
of mechanical stirrer involved, and thermal insulation around the outside of
the bath. Another possibility may be that whatever the sensor is that you
are trying to calibrate may not have good thermal connection to the oil, but
the material may get good thermal connection to water, which could be why
you had better results with that.

At the end of the day, I think you are looking at the reason why people go
with a thermocouple or PT100/1000 which essentially do not need calibrating
for anything but the most critical laboratory process, and build some
electronics around that.

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