The 1951 Oldsmobile 88, like most cars of that era, has a
master cylinder located under the
hood, usually near the firewall. That's where you'd add brake fluid. There's typically a small reservoir on top of the master cylinder with a cap you can remove to check the level and add fluid.
Important Note: Always check your owner's manual (if you have it) for the specific location and instructions. And remember to use the correct type of brake fluid specified for your vehicle. Incorrect fluid can damage the system.
