Brake fluid. I cam buy inexpensive Silverhook DOT 4 or ATE DOT 4 for double the price.

Is brave fluid like car oil whre better grades are available? Or if meeting the correct grade that's good enough?

Things like life in service and lubrication properties are never mentioned.

Cheers

If they meet the required standard then the cheaper fluid is likely to do everything you need.
You just have trust it has me the standards. If you are buying from a reputable supplier then it's probably ok.
If you're buying from Facebook your DOT4 brake fluit is probable made of jam or Bisto.

From Fleet News this morning:

"Non-compliant brake fluid warning after stock still available

A second safety warning has been issued for a non-compliant brake fluid that could impact stopping distances and degrade braking systems.

The warning was issued by the Verification of Lubricant Specifications (VLS) after stock of Mannol Brake Fluid DOT 4 3002 was found to be still available and still non-compliant.

In December 2023, VLS received a complaint claiming that the product failed in critical performance areas required for safe brake operation. "

https://www.fleetnews.co.uk/news/non-complaint-brake-fluid-warning-after-stock-still-available?gutid=6419