Funny you should ask about mower spindles.
Many years ago, Dad had a International Cub Low-Boy tractor ... 1967 (I believe) with a 4-cylinder gas ... driving a deck with 3 blades. I used a generic (Zep?) #2 grease ... but it wouldn't stay in the worn bearings. Wow, what a racket they made! I forget exactly what it would do, but I knew I needed a heavier grease for the old beast. My Dad had a special grease for his Model A Ford water pump ... had the consistency of jellied cranberry sauce ... but even thicker. I tried it in the International.
After I engaged the deck, the blades sounded like a helicopter spooling up for take-off. Veerrryyy slow at first, but then they finally picked up speed and the mower worked fine. It was still pretty funny at the time.
I'd still try the Schaeffer 238 in a blade spindle application. It's not nearly as thick as that water pump grease ... just a tick thicker (and tackier) than standard #2.