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Discussion Starter #1
I have 100,000 miles on my commander and have never actually changed the brake fluid or had to add any. I just had a complete brake overhaul done.....new pads, rotors and calipers. Should I replace the fluid?
Thanls
 

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Yes you should, It can absorb water and other contaminants over the years. With all those gaskets treat them to the best.
 

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Brake fluid is hydroscopic and it absorbs water. This is part of the reason that the system is sealed. Water in the fluid can give you a spongy brake.

I do not know the recommended interval but I would flush your system if it has never been flushed.

Starting at the wheel that is fartherest from your master cylinder, (right rear wheel) you would bleed the brake into a glass container while watching the color of the fluid. Make sure that the reservour (sp) does not get empty as you bleed the system. Then move to each wheel as you get closer to the master cylinder.

Make sure that you get the correct grade of brake fluid.

Also, because brake fluid absorbs water you should try to use a new can up and discard it if it has been opened for awhile.

Basically what you are doing is flushing the system until all of the old fluid is replaced with new fluid.

I am not an expert but this is my opinion.
 

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Discussion Starter #4
Thanks guys. I'll get on that this weekend. I appreciate the input.
 

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Keep in mind the Commander has recommended for brake fluid DOT 3. Sure you can use DOT 4 if you want, it has higher boiling points, but DOT 3 lasts longer and absorbs less moisture than DOT 4. So, think about it, DOT 3 really is the better fluid, unless your brakes get so hot they require the higher temp, but shorter lasting, less durable DOT 4.

As well, there are several brands of DOT 3 and 4 fluid, that use the better additives to achieve the characteristics that is needed, so they are the best of both worlds, they absorb moisture slower than DOT 3, as durable and can go to temps even higher than DOT 4. Castrol GTLMA is one, Valvoline DOT 3 & 4 Brake Fluid is another.

Like mentioned, the brake fluid will absorb moisture right out of the air, even if you don't open the brake system, it can suck right through the seals.

The good about brake fluid absorbing moisture is that if water ever got into your brake system, instead of descending to the lowest point of the lines and laying there, rusting a hole in the line to make your brake fails, it will absorb the water and hold it in the fluid. The bad about that, over the years the brake fluid will get more and more moisture absorbed in it, that will lower its boiling point temp dropping and one day when you really task your brakes and get them really hot, the fluid may boil and turn to steam and steam compresses, and thus no brakes. As well, the moisture in the fluid will allow sludge and gum to form and can start some corrosion in parts of the brakes.

Also, remember, when the manufacturer says that a fluid will last the life of the vehicle, they are assuming the vehicle is only going to last 100k miles. So change your brake fluid.

Power Steering fluid is a good one to change as well before the life of the vehicle. And if you have a Hemi with the hydraulic driven fan, that is powered by the PS system, and how often those have failed, it might be good to replace that fluid with the Correct Fluid (the Commander uses a hybrid PS/Hydraulic fluid you can only get from the Dealer).
 

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Discussion Starter #6
Keep in mind the Commander has recommended for brake fluid DOT 3. Sure you can use DOT 4 if you want, it has higher boiling points, but DOT 3 lasts longer and absorbs less moisture than DOT 4. So, think about it, DOT 3 really is the better fluid, unless your brakes get so hot they require the higher temp, but shorter lasting, less durable DOT 4.

As well, there are several brands of DOT 3 and 4 fluid, that use the better additives to achieve the characteristics that is needed, so they are the best of both worlds, they absorb moisture slower than DOT 3, as durable and can go to temps even higher than DOT 4. Castrol GTLMA is one, Valvoline DOT 3 & 4 Brake Fluid is another.

Like mentioned, the brake fluid will absorb moisture right out of the air, even if you don't open the brake system, it can suck right through the seals.

The good about brake fluid absorbing moisture is that if water ever got into your brake system, instead of descending to the lowest point of the lines and laying there, rusting a hole in the line to make your brake fails, it will absorb the water and hold it in the fluid. The bad about that, over the years the brake fluid will get more and more moisture absorbed in it, that will lower its boiling point temp dropping and one day when you really task your brakes and get them really hot, the fluid may boil and turn to steam and steam compresses, and thus no brakes. As well, the moisture in the fluid will allow sludge and gum to form and can start some corrosion in parts of the brakes.

Also, remember, when the manufacturer says that a fluid will last the life of the vehicle, they are assuming the vehicle is only going to last 100k miles. So change your brake fluid.

Power Steering fluid is a good one to change as well before the life of the vehicle. And if you have a Hemi with the hydraulic driven fan, that is powered by the PS system, and how often those have failed, it might be good to replace that fluid with the Correct Fluid (the Commander uses a hybrid PS/Hydraulic fluid you can only get from the Dealer).
Thank you very much for this reply. I understand fully now. I really appreciate it. That said....which of the two better fluids you mentioned would be your choice? The Castrol or the Valvoline? Also, how much should I get to redo/flush the whole system?
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IMO, Castrol GTLMA is the better brake fluid, the problem is it is harder and harder to find in the stores, while the Valvoline DOT 3&4 fluid is pretty easy to find.

The classic british sports car guys use Castrol GTLMA, the british used different types of seals in their brake system in the 70's and earlier, that is NOT compatible with U.S. brake fluid, they require a vegetable oil based brake fluid. The owners found that Castrol GTLMA works in their vehicles. And no Castrol GTLMA is NOT vegetable oil based, because it uses the better additives to give it the desired properties it is just much easier on seals.

Usually a 32 oz bottle will be enough to do all the brakes, use a clear tube you can get at the hardware store, so you can see the fluid as it comes out of the bleed screws, when the color changes to the lighter/clear fluid then you know you got all the old fluid out.

Without the special dealer tools, you can't activate the ABS pump to swap out the fluid in the pump, no big deal, its a small amount and you got most of it changed, the next time the pump activates it will mix new fluid into the pump. Older ABS system, could only be bleed with the Dealer tool, new systems, like the Commander can be bleed like normal, you just won't get the tiny bit in the ABS pump swapped out.
 
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