add on hydrogen fuel systems? are they as good as some claim. is there any long term problems?

Absolutely bogus, a scam, a ripoff. Go to the ‘search’ box and type in HHO, and read all about this nonsense.

Texases took the words right out of my mouth.

The linked article might interest you

The long-term problems are in the area of your wallet, once it has lost the money that you wasted if you bought into this scam pseudo-science.

Do you recall the old saying, “A fool and his money are soon parted”?
Don’t be a fool.

SCAM! Nothing more.

Don’t waste your money.

Buy the magnets for your fuel line instead, or the “pills” that you drop in your gas tank.

Those work. I guarantee it.

But not the hydrogen systems. They’re worthless.

KIDDING! Just kidding.

NONE of the add-on devices you see advertised will increase fuel mileage. They are all scams, designed only to relieve you of your hard-earned money.

Don’t fall for any of them.

The only addition that really works is the Incredible Edible Egg, Put one on your dash and try not to let it roll off.