weigh error?

This might be a really dumb question sorry in advance... 1. Do you use fluid ounces (versus regular ounces) when making soap? 2. Do you work with ounces or grams? I would like to work in grams but my scale doesnt show the decimal points (ie. 120.2 g) instead it would just show 120 grams. Would...

I had all my oils melted, then mixed and decided to weigh just in case. And what should be 800.86 grams oi oil only weighs 761.00 grams! As I weighed each oil, I put away the bottle. But one bottle was still on the counter - the castor oil, which should be 40.04 grams in this recipe. I...