The four seat belts in between the bucket seats on the Aquamist car were always, for lack of a better word, stiff. I finally got the motivation to do something about them. Took them out of the car and put them in a bucket of hot water and laundry detergent. The water almost immediately turned brown. After a 1/2 hour the water was nearly black! I agitated them periodically, I took them out, scrubbed them and hoses them off. What a difference! The date code and certification labels were brown. They're now white! And the belts are supple soft now. They honestly look brand new now. Amazing!