Laundry: Just got in HE washing machine. I have a lot of regular detergents left. Do I use old detergents non HE?

"HE" machines use less water, so they require much less detergent to clean similar loads of clothes. 

'HE' detergents clean the same, they just make less suds

You can use non 'HE' detergents in an 'HE' machine, just cut the amount way down.

For example, my old top loader used 4/5 of a cap full of liquid Tide per load, and my newer front loader will use 1/6 of a cap full for a similar load, and cleans the same.

We don't use 'HE' detergent, and have had no issues.

Get rid of it. The HE detergent is very different. Use the liquid HE as so little water is generated in these washers that the pods or dry detergent can't dissolve as well.

Don't - they can over sud and cause problems!