DOT 3 vs DOT 4 Brake Fluid

[NXTGENAutomotive]

Dot 4 is more hydroscopic than dot 3. Good thing our Jeeps never see water! That being said, our Jeeps will never generate the heat as vehicles on the track. As a daily driver, Dot 4 will work but not needed.

OP, stick with Dot 3. You will not benefit or feel a difference.

We are all welcome to do exactly as we please with our Jeeps. I'm just trying to help the OP make an educated choice and this is factually inaccurate.

1) The braking system is a closed, sealed system and subjecting the Jeep to water has no impact on what braking fluid you use.

2) Dot 4 has a higher boiling point, and the moisture that is being generated is from the heating of the fluid. The closer you get to the fluids boiling points ( wet and dry), the more moisture you will be subjecting it to. Although dot 4 will need to be replaced more often, you should be generating less moisture technically speaking with dot 4 vs 3. The boiling point differences are notable and even 1 really hard stomp on the brakes in an emergency with a full load in the bed or a trailer could easily foul the Dot 3.

3) Dot 4 is definitely not a track fluid, at least not today. Beyond our Jeeps, we own and tune some pretty high performance BMWs, some well over 700Hp. If those cars were going to the track, Dot 4 would NOT be the fluid in 2025. We would use Dot 5.1 (Dot 5 is not compatible with 3 or 4 and 5.1 is).

4) Dot 4 is simply a more modern and higher performance replacement for DOT 3. That 100% does not mean track use. Dot 3 is a very basic fluid, and Dot 4 has benefits for towing, hauling, high speed stopping on the hwy, and repeated hard braking on the trials. These are all higher performance uses that are a great fit for Dot 4 over 3 and for sure apply to our Jeeps. There is no downside to using Dot 4 other than it needs to be replaced more often. If you are towing, or wheeling often, more frequent changes are not the worst thing anyway, unless it is a leased vehicle, then YOLO...

You will feel a difference if you regularly apply the brakes under a load with a higher performance fluid.

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[biplaneguy]

Dot5 or even 6 is more for track cars, where brakes get really hot.

Not just track cars... I used to own a 1975 DJ5D ("Delivery Jeep", aka postal Jeep) which specified DOT5 fluid. Makes sense; lots of brake usage in that application.

 

[Lost1wing]

We are all welcome to do exactly as we please with our Jeeps. I'm just trying to help the OP make an educated choice and this is factually inaccurate.

1) The braking system is a closed, sealed system and subjecting the Jeep to water has no impact on what braking fluid you use.

2) Dot 4 has a higher boiling point, and the moisture that is being generated is from the heating of the fluid. The closer you get to the fluids boiling points ( wet and dry), the more moisture you will be subjecting it to. Although dot 4 will need to be replaced more often, you should be generating less moisture technically speaking with dot 4 vs 3. The boiling point differences are notable and even 1 really hard stomp on the brakes in an emergency with a full load in the bed or a trailer could easily foul the Dot 3.

3) Dot 4 is definitely not a track fluid, at least not today. Beyond our Jeeps, we own and tune some pretty high performance BMWs, some well over 700Hp. If those cars were going to the track, Dot 4 would NOT be the fluid in 2025. We would use Dot 5.1 (Dot 5 is not compatible with 3 or 4 and 5.1 is).

4) Dot 4 is simply a more modern and higher performance replacement for DOT 3. That 100% does not mean track use. Dot 3 is a very basic fluid, and Dot 4 has benefits for towing, hauling, high speed stopping on the hwy, and repeated hard braking on the trials. These are all higher performance uses that are a great fit for Dot 4 over 3 and for sure apply to our Jeeps. There is no downside to using Dot 4 other than it needs to be replaced more often. If you are towing, or wheeling often, more frequent changes are not the worst thing anyway, unless it is a leased vehicle, then YOLO...

You will feel a difference if you regularly apply the brakes under a load with a higher performance fluid.

Go cross a stream a few times and pull the boots off of the caliper piston. Those boots also fail over time. The piston seals don't completely wipe away the moisture that got in.

No average person can get in a jeep and tell if it has dot 3 or dot 4. Maybe after the second lap at road Atlanta you could tell but that wouldn't be the average person. If you are changing fluid from dot 3 to dot 4 you may see a difference just because of air and moisture being removed and not because of the type fluid.

 

[Lost1wing]

Not just track cars... I used to own a 1975 DJ5D ("Delivery Jeep", aka postal Jeep) which specified DOT5 fluid. Makes sense; lots of brake usage in that application.

4+ was in German and asian motor cycles. If I recall 4+ was not compatible with dot 3.

 

[Lost1wing]

We are all welcome to do exactly as we please with our Jeeps. I'm just trying to help the OP make an educated choice and this is factually inaccurate.

1) The braking system is a closed, sealed system and subjecting the Jeep to water has no impact on what braking fluid you use.

2) Dot 4 has a higher boiling point, and the moisture that is being generated is from the heating of the fluid. The closer you get to the fluids boiling points ( wet and dry), the more moisture you will be subjecting it to. Although dot 4 will need to be replaced more often, you should be generating less moisture technically speaking with dot 4 vs 3. The boiling point differences are notable and even 1 really hard stomp on the brakes in an emergency with a full load in the bed or a trailer could easily foul the Dot 3.

3) Dot 4 is definitely not a track fluid, at least not today. Beyond our Jeeps, we own and tune some pretty high performance BMWs, some well over 700Hp. If those cars were going to the track, Dot 4 would NOT be the fluid in 2025. We would use Dot 5.1 (Dot 5 is not compatible with 3 or 4 and 5.1 is).

4) Dot 4 is simply a more modern and higher performance replacement for DOT 3. That 100% does not mean track use. Dot 3 is a very basic fluid, and Dot 4 has benefits for towing, hauling, high speed stopping on the hwy, and repeated hard braking on the trials. These are all higher performance uses that are a great fit for Dot 4 over 3 and for sure apply to our Jeeps. There is no downside to using Dot 4 other than it needs to be replaced more often. If you are towing, or wheeling often, more frequent changes are not the worst thing anyway, unless it is a leased vehicle, then YOLO...

You will feel a difference if you regularly apply the brakes under a load with a higher performance fluid.

Agreed! 2-4 anyhow. None of this pertains to our Jeeps. Rock crawling and some steep decents may encounter higher temps, but not enough to warrant dot 4 that would require more frequent flushes. Dot 3 is fine.

 

[NXTGENAutomotive]

Go cross a stream a few times and pull the boots off of the caliper piston. Those boots also fail over time. The piston seals don't completely wipe away the moisture that got in.

But this applies to Dot 3 the same as Dot 4, and is a constant. Just because Dot 4 is a bit more hydroscopic does not mean Dot 3 is not. In this situation, you would be contaminating both fluids. When this happens it reduces the fluids boiling point and efficiency. Being that as it may, the Dot 4 would still be the superior fluid. Because if a degraded fluid has a reduced boiling point, a degraded 4 is still going to perform better than a degraded 3. This is not a 4 specific thing, and if you are playing in the water, you should consider changing the brake fluid and possibly diffs depending on how deep as required.

No average person can get in a jeep and tell if it has dot 3 or dot 4. Maybe after the second lap at road Atlanta you could tell but that wouldn't be the average person. If you are changing fluid from dot 3 to dot 4 you may see a difference just because of air and moisture being removed and not because of the type fluid.

Again, we are not talking about DD duty, as I have stated several times. Plenty of people on here tow, haul and wheel. All of these situations will have a noticeable impact on brake fade with a higher temp fluid. Dot 3 has a pretty low wet boiling point. I promise you can quickly degrade that fluid within a several mile portion towing in a mountain pass. That's not uncommon use for owners here, no one is talking about track laps

 

[Lost1wing]

But this applies to Dot 3 the same as Dot 4, and is a constant. Just because Dot 4 is a bit more hydroscopic does not mean Dot 3 is not. In this situation, you would be contaminating both fluids. When this happens it reduces the fluids boiling point and efficiency. Being that as it may, the Dot 4 would still be the superior fluid. Because if a degraded fluid has a reduced boiling point, a degraded 4 is still going to perform better than a degraded 3. This is not a 4 specific thing, and if you are playing in the water, you should consider changing the brake fluid and possibly diffs depending on how deep as required.





Again, we are not talking about DD duty, as I have stated several times. Plenty of people on here tow, haul and wheel. All of these situations will have a noticeable impact on brake fade with a higher temp fluid. Dot 3 has a pretty low wet boiling point. I promise you can quickly degrade that fluid within a several mile portion towing in a mountain pass. That's not uncommon use for owners here, no one is talking about track laps

You are right about towing on a downhill incline. I don't know the next time I will tow with the JT, but I will get some temp readings of the front calipers. I see those Gladiator tour rigs coming down Pikes peak all of the time. I'm sure they have the same brake fluid in them from their delivery date.

 

[NXTGENAutomotive]

You are right about towing on a downhill incline. I don't know the next time I will tow with the JT, but I will get some temp readings of the front calipers. I see those Gladiator tour rigs coming down Pikes peak all of the time. I'm sure they have the same brake fluid in them from their delivery date.

I’m originally from Phoenix but have lived in So-Cal a long time. I’m mostly driving across the SW US and this is mountainous and hilly terrain. See lots of Gladiators out on the roads with travel trailers here.

Where you live is definitely also a factor/ consideration.

 

[smlobx]

Just curious as I’ve never thought about it.

Can you mix DOT 3 and DOT 4 fluid together? I would think it’s very hard to completely flush the fluid out 100%.

In my Porsche Cup car our brake fluid came in 2 colors so that when we did a change before each race it was easy to see when the new fluid had made it to the calipers… way overkill for a Jeep.

 

[Sweetums]

Just curious as I’ve never thought about it.

Can you mix DOT 3 and DOT 4 fluid together? I would think it’s very hard to completely flush the fluid out 100%.

In my Porsche Cup car our brake fluid came in 2 colors so that when we did a change before each race it was easy to see when the new fluid had made it to the calipers… way overkill for a Jeep.

Back in the day they used to make blue brake fluid so you could visibly see when the old fluid was completely out of the system. The idea is you would alternate at each fluid change. Unfortunately it hasn't been available since 2013 thanks to DOT mandating that brake fluid be amber or clear only.

I think you can still buy it for motorsport/track use only in some locations, but it will probably void warranties if a dealer catches it in your system.

 

[NXTGENAutomotive]

Just curious as I’ve never thought about it.

Can you mix DOT 3 and DOT 4 fluid together? I would think it’s very hard to completely flush the fluid out 100%.

In my Porsche Cup car our brake fluid came in 2 colors so that when we did a change before each race it was easy to see when the new fluid had made it to the calipers… way overkill for a Jeep.

3, 4 and 5.1 are compatible to mix. 6 is not going to be needed on a Jeep.

I remember the days of alternating the Ate type 200 blue with the amber for German cars. They made the blue illegal, at least in the USA so now they are all amber.

I use Ate SL.6 low viscosity Dot4 on every vehicle in my stable, Jeeps and BMWs. Good stuff at a good price.

 

[Sweetums]

3, 4 and 5.1 are compatible to mix. 6 is not going to be needed on a Jeep.

I remember the days of alternating the Ate type 200 blue with the amber for German cars. They made the blue illegal, at least in the USA so now they are all amber.

I use Ate SL.6 low viscosity Dot4 on every vehicle in my stable, Jeeps and BMWs. Good stuff at a good price.

It's illegal for street use, but still available if you pinky-promise to only use it on the track.

 

[NXTGENAutomotive]

It's illegal for street use, but still available if you pinky-promise to only use it on the track.

Pinky promise!!

In all seriousness, with the Automotive business I am swapping cars every few years and have several cars. So, none in the stable are a good fit for that type of Dot 4 anymore. The ate type 200 and super blue version are not low viscosity. Plenty of vehicles out there still to take advantage of it though.

There has been a lot of technology into brake fluids, engine oil and transmission fluids over the last decade. The newer cars with advanced ABS and stability control really benefit from a fluid much lower viscosity than the older formulation. So in many cases you would go 5.1 over something like ate type 200 Dot 4.

Back in those days, you would also use a 5w-30 oil for street use and in a performance setting or a tuned car, OW-40 was much preferred, even on a lightly modified 2.0T. Today, most of these come factory filled with really high quality 0w-20. You would never dream of running pee water like that 'back in the day' especially on a modified turbo car. But we tried some good 0w-40 in newer cars and they literally choked on it, even a thinner variety of 0w-40. The oil analysis was absolutely perfect at 5,500 mile intervals on a decently modified B58 6 cylinder turbo with the 0w-20, with regularly very spirited street driving. On the track, you could go up to 0w-30 at the most.

So, the technologies are legit, and even us older-school gear heads have to keep up with it sometimes.

 

[Sweetums]

The next thing is full brake-by-wire. Brembo has announced an all-electric brake caliper with no hydraulics of any kind.

Count me out for that, it's a terrible idea. I'm never getting in a car with brake-by-wire.

 

[Minty JL]

F@ck it, use nothing but Castrol SRF, an absolute bargain at $80 per liter. I have to use this stuff in the motorcycle because it has a habit of cooking the rear brake fluid with the exhaust heat. Since it uses a thimble-full, I use the vacuum sealer from the kitchen to reseal the bottle.

Yeah if I'm cooking the brake fluid, I'm doing it wrong or over driving the capabilities of the Gladiator.

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