Seal material. Wrong fluid can do wonderful things when two fluids meet!
Here's a brake master gasket for example that was topped with the wrong fluid. Wish I could find a similar miracle for my pecker... View attachment 1716333793
LOL.....I bough a Chevette back in '85 that someone did that to.......Ended up replacing everything as the stuff turned to jello. I actually parked my Demon back then to take advantage of the Chevette's gas mileage while I was in school.