Shop Press

Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle.

From the creative minds at:

FEATURE STORY

Hot Off the Press

Why are Muffin Tins in the Shop? (VIDEO)

Description Keeping track of small parts during a job can be tricky, but there’s a cheap and effective way to solve that problem. Old muffin tins are perfect for storing and labeling auto parts. (Just don’t mix up your “shop” muffin tin with the one in your...

Service Writing Tip: Justify Your Recommendations

Writers, are you as tired as I am of getting lambasted by customers when you recommend work beyond the symptoms displayed by a vehicle that was brought to your shop? Between TikTok videos and fuel touching $5 per gallon (or six, for those of you burning diesel), it...

Start Fasteners by Hand Before Using Power Tools (VIDEO)

Description Cordless power tools are stronger and more common than ever, and they help to speed up all kinds of automotive work. But cross-threading or stripping a fastener can bring progress to a halt in an instant. Start by hand-threading fasteners before reaching...

Take a Step Back to Take a Step Forward (VIDEO)

Description Ever get up to your elbows in a diagnostic problem, only to wind up right where you started an hour later? It may be time to take a step back to get fresh perspective. That way, you can reevaluate the problem and potentially spot issues you’ve...

How to Hang Onto a Tricky Nut or Bolt (VIDEO)

Description Having trouble hanging onto a nut or bolt, especially in a part of the vehicle with minimal access or tight corners? Try these tips and tricks for keeping fasteners where you want them during installation.Related Videos

Service Managers: Buy Brake Fluid by the Pint

by | Jun 11, 2026

If you’re in charge of ordering the supplies for your shop, volume discounts are great when they come along. Sniff them out where you can. But brake fluid is different! Buy it in bulk, but buy it in the smallest containers you can get away with. The reason? Brake fluid is hygroscopic. And the boiling point matters more than ever.
To wit: if you read most any master cylinder cap, you’ll be instructed to use brake fluid from a sealed container. That’s to ensure that the fluid doesn’t suck moisture out of the ambient air. (That’s what “hygroscopic” means.) When brake fluid becomes waterlogged, the boiling point of the fluid is lowered, and the water can actually boil off. Fluid, as we learned from Pascal, is incompressible, but that’s not true of a gas (like steam). If the water turns gaseous, the pedal can travel without compressing the fluid and then moving the pads or shoes, which is obviously not good.

Couple this with the rise of vehicles using DOT 4 brake juice. This differs from the more common DOT 3 only in terms of having a higher boiling point. Why? Brakes are being asked to do more work that generates more heat, and the hydraulic fluid needs to work harder as well. That fact, coupled with ever-more-intricate ABS systems with faster processors and controllers, means it’s more important than ever to keep water out of the system.

Buying small, sealed containers can help you do this. Sure, if you’re finally plumbing up that old project car, buy a quart or even a gallon for the bench bleed on the master and gravity bleed of the lines and hoses that will follow. But you’ll want to toss it not long after, and for most regular fluid swaps done in tandem with a brake job, a pint or two will do you just fine.

The scant savings from buying in bulk might not be all that prudent. So get your oil in a drum—but brake fluid should be in airline bottles only.

The articles and other content contained on this site may contain links to third party websites. By clicking them, you consent to Dorman’s Website Use Agreement.

Related Articles

Shop Press Comment Policy

Participation in this forum is subject to Dorman’s Website Terms & Conditions. Please read our Comment Policy before commenting.

Subscribe
Notify of
guest
0 Comments
Newest
Oldest Most Voted