Don't top off brake fluid?

Keith…You are right that it is a not circulated through the system. But, that is not how I believe the moisture content is lessened. Water will migrate in a median, whether it be soil or in suspension in a fluid from area of greater to lesser concentration.

With a lower concentration around the brake pads, the wet boiling point rises there and that’s a good thing, on a long mountainous road, far from home…

Don’t forget too, you have added buffer if a leak does developes… far from home, in a mountainous area, now add a Peterbuilt from Duel on your tail… :=)

I’d keep it full. The more fluid in the reservoir, the more volume there is to compensate somewhat for any contamination. And you definitely don’t want it to get low enough that you have to bleed the system. If you wait until the warning light comes on like the shop said, you’re essentially waiting until your braking is compromised and using this as an indication of when to replace the brakes. This makes about as much sense to me as waiting until the oil light comes on to add oil to your car.

A quick peek at the pads is all you need to do to determine if they need replaced.

Knowing the type of vehicle might help too. It’s been my experience that rear drum brakes that are badly worn or out of adjustment will influence the fluid level more than rear discs.

I would avoid this nationwide car shop as you refer to it for a number of reasons.
One is tht a 30k miles service is a comparatively major service and inspecting/topping off the fluid should be part of that service.
Two is that it’s stupid to use brake fluid level to gauge brake wear.
Three is telling you to wait until the brake light comes on to have the brakes inspected/repaired. What happens if it comes on as the pedal sinks to the floor and you go sailing through a stop sign into heavy traffic?

What I would be really wondering about right now is just how much this apparent chain shop actually did to your car as to any service. If they’re willing to overlook the brake fluid and lay BS like that on you I would not trust them on anything else.

Who are you, why did you resurrect an 8-year-dead thread to tell us we’re wrong, oh and show us your engineering degree.

If you top off the brake fluid just because it dropped slightly due to pad wear, then when you replace the pads you will leak brake fluid out the top of the reservoir. That’s what people who understand cars call a Bad Thing™.

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It has nothing to do with laziness. It’s simply not necessary and can create problems, and therefore is not an advisable thing to do. If your brake fluid is low, and there is no leak, then that’s a good indication that you haven’t checked your pad thickness in too long and you should probably do that now and then replace the pads that are worn out before you go metal-to-metal rather than topping the fluid off and thinking you were a good mechanic.

Note that that doesn’t mean any of us are saying “use your brake fluid level as a pad thickness indicator.” Instead, use your brake fluid level as an indication that you have been negligent in checking your pad thickness and should do better in the future.

The bottom line is that if the brake fluid is low, there is a reason for it, and you need to find and remedy that reason. Either you have a leak, or you have low pads. Just topping it off is putting a bandaid on the symptom and not fixing the root cause.

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People who understand cars know when to use a turkey baster!

There’s no reasonable argument against keeping brake fluid up to the full level.

There is no reasonable argument for topping off the brake fluid without finding out why the brake fluid was low in the first place, and fixing it before your brakes fail.

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Yes. A drop in fluid level can mean a leak - very dangerous - so find out. It can mean wear in the pads - take a look and find out. Knowing stuff is a good thing!

As Tom and Ray used to say, engineers are the worst. :wink:

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Ask the manufacturers what exactly? And are you an engineer or factory trained? And if your brakes fail, why are you still trying to drive the vehicle?

Modern brake master cylinder reservoirs have the min level about half way or more up from the bottom so even at minimum, there is plenty of fluid for a few stops. But your vehicle, you do what you think is best. I’ll do what I think is best for mine.

It’s ridiculous that anyone would argue for mindlessly dumping brake fluid in a system that has apparent fluid loss without finding out why it’s low in the first place and fixing the problem.

Hint: If it’s the pads, and you replace the pads, the fluid will be back up where it should be, and adding fluid is not necessary.

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Because you said in your overly abrasive OP that we should “always” top off brake fluid. I’ve shown you how you were wrong, and yet you keep insisting.

Topping off is a dumb move. If it’s the pads, replace the pads and you don’t need to top off. If it’s a leak, fix the leak and then exchange all of the brake fluid to make sure the hole didn’t allow contaminants to get into the system - don’t just top it off.

How many times are you going to vie for the last word?

Knowing how many old cars are out there that predate mandated ABS, I’m going to have to ask you to cite your source for that figure.

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Don’t mind at all.

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How about my 2017 Camry then?

It doesn’t say to keep it topped off at all times.
In fact, it wouldn’t have a MIN line if it didn’t allow for a RANGE of fluid over time.
The maintenance guide also only says to adjust fluid levels at certain time/mileage intervals.
According to you, if it ever falls even slightly below full, I should add fluid to keep it at MAX.
That’s ridiculous…

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This is the information from the 2017 CTS6 owners manual, who should the owners trust, you or General Motors?

Checking Brake Fluid

With the vehicle in P (Park) on a level surface, the brake fluid level should be
between the minimum and maximum marks on the brake fluid reservoir.

There are only two reasons why the brake fluid level in the reservoir may
go down:

. Normal brake lining wear. When new linings are installed, the fluid level goes back up.

. A fluid leak in the brake hydraulic system. Have the brake hydraulic
system fixed. With a leak, the brakes will not work well.

Always clean the brake fluid reservoir cap and the area around the cap
before removing it.

Do not top off the brake fluid. Adding fluid does not correct a leak. If fluid is
added when the linings are worn, there will be too much fluid when
new brake linings are installed. Add or remove fluid, as necessary, only when
work is done on the brake hydraulic system.

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Are you experiencing bliss right now?

Does willful ignorance lead to willful bliss?

It appears that Harold is left the building.

The only time I normally use brake fluid Is when I do a brake job and the fluid in the in the master cylinder is anything but clear. Then I flush the fluid out after doing the brakes. I noticed recently that my fluid is getting near the min. so as soon as the single digit temps leave I will check my pads and if they are more than 3/4 I will replace the pads and usually the rotors and flush the fluid. Since I onledo a brake job every couple of years now, it used to be 7 or 8 I think it is stupid to open a bottle of fluid that will go to waste when the level has not gone below the minimum. I wonder why the Cadillac engineer thinks they put a minimum level on it if no one is supposed to pay attention to it.