I need to know
1.5 is the limit of sodium, not salt. Regular salt is made out of Na and Cl, you gotta eat like 4 grams of salt to get 1.5grams of sodium.
6 grams is kinda overshoot if you dont get like 5000mg of potassium from diet, which is pretty hard tbh.
If you want to know how much sodium you need to consume without breaking your body up, just calculate your potassium intake and divide that number by 2.
Where are you getting the 6g number? How much is correct or too much is completely dependent on you and your activity. Hyper active people need more, people who eat really low carb diets need more. But there is no one size fits all number.
I would say the range is 5-15g of table salt each day is the upper limit depending on your diet, water consumption and activity level.
I recommend a book called The Salt Fix by Dr. James DiNicolantonio, it might change your life.
Edit: and remember to distinguish salt from sodium