How to perform brake fluid health check?

[notsure11]

Tesla Model 3 manual says the car's brake fluid needs a "health check" every 2 years. It looks like there are brake fluid liquid tester pens like this that measure the moisture content, and then there are test strips like this that measure copper content.

Do I need to test using both methods? Or can I just use the tester pen to check moisture content only? I have a 2018 Model 3 with about 10,000 miles on it, and I haven't changed the brake fluid yet. Thanks!

 

[smatthew]

Don't worry... 120K miles and haven't changed the brake fluid yet. You're good.

 

[KenC]

I used a pen to test after 2yrs.

 

[3sr+buyer]

Don't worry... 120K miles and haven't changed the brake fluid yet. You're good.

Vehicle companies that recommend checking or changing the brake fluid often recommend it by time regardless of mileage, since brake fluid performance degrades based on water absorption over time (more water = lower boiling point, resulting in greater risk of boiling the brake fluid under hard braking).

 

[Leeclanual]

First ‘real’ service is at 4 years? Something about cooling fluid for the battery? What else?

 

[notsure11]

I thought I didn’t have to worry about cooling fluid?

 

[rpiotro]

I thought I didn’t have to worry about cooling fluid?

I don't recall seeing that either.

 

[texas_star_TM3]

Don't worry... 120K miles and haven't changed the brake fluid yet. You're good.

that seems a bit excessive ... granted with regen brakes aren't used that much but with ICE cars needing a brake fluid change every 3-4 yrs or after 40k+ miles... i wouldn't go 3x that even in an EV

 

[android04]

Tesla Model 3 manual says the car's brake fluid needs a "health check" every 2 years. It looks like there are brake fluid liquid tester pens like this that measure the moisture content, and then there are test strips like this that measure copper content.

Do I need to test using both methods? Or can I just use the tester pen to check moisture content only? I have a 2018 Model 3 with about 10,000 miles on it, and I haven't changed the brake fluid yet. Thanks!

I used both to test my brake fluid at about 2 years (40,000 miles) and everything tested good. I'd say hey both since they are cheap enough and test every 2 years. Brake fluid absorbs moisture and will eventually become less effective with time. The electronic tester will check for that. The test strip checks for corrosion of the brake lines. I would get the test strips that are just for brake fluid instead of brake+cooling.

 

[Leeclanual]

I thought I didn’t have to worry about cooling fluid?

 

[Knightshade]

Brake fluid failure is kind of insidious- because you don't know there's a problem until it's too late.

Hence folks who haven't changed their fluid in 10 years who think it's "fine" because the car still performs a normal stop ok.

It absorbs moisture over time just by existing--- this lowers the boiling point of the fluid.

Again not an issue if you're not doing any HARD braking.

But if you ever do, in an emergency from high speed for example, old fluid will boil much more easily.

See attached for how DOT3 brake fluid boiling point drops with age... at just 3 years it's already dropped considerably....it's pretty much at the minimum of DOT and OEM requirements....and will keep getting worse over time.

Is that still "fine"? If you're regen braking, or rarely using the brake pedal, and never often or hard? Sure.

If you suddenly need to slam on the pedal at 75 mph in an emergency? Maybe not.

 

[Knightshade]

Your info is out of date I'm afraid. Coolant never needs to be touched.

(actually I'm thinking you posted a chart that's both out of date- and for the wrong model too since it mentions fob batteries)

Model 3 Owner's Manual | Tesla

Determine when you should bring your car to service and learn how to perform daily and monthly checks to ensure optimal performance.

www.tesla.com

Every 2 years: Cabin air filter replacement and Brake fluid health check (replace if needed)

A/C desiccant bag replacement every 6 years.

Clean and lubricate brake calipers every year or 12,500 miles (20,000 km) if in an area where roads are salted during winter

Rotate tires every 6,250 miles (10,000 km) or if tread depth difference is 2/32 in (1.5 mm) or greater, whichever comes first

That's it.

If one is lazy and doesn't want to test their fluid I'd suggest doing it at least every other 2-year-filter change (so once every 4 years).

 

[Leeclanual]

Your info is out of date I'm afraid. Coolant never needs to be touched.

(actually I'm thinking you posted a chart that's both out of date- and for the wrong model too since it mentions fob batteries)

Model 3 Owner's Manual | Tesla

Determine when you should bring your car to service and learn how to perform daily and monthly checks to ensure optimal performance.

www.tesla.com

That's it.

If one is lazy and doesn't want to test their fluid I'd suggest doing it at least every other 2-year-filter change (so once every 4 years).

Possibly… I found the mx support document my sales rep emailed me after buying my M3 in Dec 2018… so looks like no coolant mx required in the updated chart. The chart I uploaded was specific to the Model 3 back in 2018/19.

 

[TLLMRRJ]

Just changed the brake fluid on my 2 year old Model 3, and it feels good to be nice the car. Brake fluid is cheap, and it's easy to do with a vacuum bleeder, especially if you combine the job with rotating the tires.

The original brake fluid was already starting to look discolored, which is also an indicator of absorbing moisture. Most DOT 3 brake fluids are clear as water when fresh.

Go with DOT 3 because it resists absorbing water more than DOT 4, and unless you track your car, you'll never need the higher boiling point of DOT 4.

 

[thesmokingman]

High end fluids don't need to be changed for 3 years, like ATE or SRF. The irony is that the guys I know that run SRF change their fluid every year and SRF is kind of expensive. I use ATE Superblue myself... I like the blue lol even though the Feds made them change the color.

 

[TLLMRRJ]

Don't worry... 120K miles and haven't changed the brake fluid yet. You're good.

No offense, but never ever buy a used car from "smathew"

 

[rpiotro]

No offense, but never ever buy a used car from "smathew"

But what if he lives in that coastal desert in Chile? The driest spot on the planet. Then it would be OK to never change brake fluid?

 

[android04]

Possibly… I found the mx support document my sales rep emailed me after buying my M3 in Dec 2018… so looks like no coolant mx required in the updated chart. The chart I uploaded was specific to the Model 3 back in 2018/19.

Yeah, your chart was what was recommended then. But Tesla changed it in 2019, IIRC. No more recommended coolant check out replacement. Here's the current info, though not in nice chart form Car Maintenance

 

[355rockit]

I use brake fluid test strip. Brake Fluid Testing | Brake Strip Brake Fluid Testing | Brake Bleeder

You can get a pack of 15 on Amazon for $20. As was noted by other replies, brake fluid absorbs water and can cause rusting of the caliper internals if not changed at intervals. I do a brake fluid flush every 2 to 3 years on my cars.

 

[TLLMRRJ]

But what if he lives in that coastal desert in Chile? The driest spot on the planet. Then it would be OK to never change brake fluid?

Does driest spot on the planet mean absolutely zero humidity?