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I just did the Service B on my 2015 GLA250. I also replaced the brake fluid based on the mileage. The brake bleeder kit I used made it a pretty simple one-person job. Pretty excited about the money I saved doing this myself.
 

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Congrats. These really are quite simple to maintain ... once you've done it once.

FWIW, I take pictures of the process and the odometer to put in the car's book (along with receipts) as a record of maintenance and running costs.
 

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Congrats. These really are quite simple to maintain ... once you've done it once.

FWIW, I take pictures of the process and the odometer to put in the car's book (along with receipts) as a record of maintenance and running costs.
Great idea to take pics. I have the receipts, but will start adding pics as well.
 

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I need some thoughts on the brake fluid flush requirement. Is the two year brake fluid flush required due to elapsed time or miles travelled. If a car is only driven 7K miles in two years (instead of more typical 20K miles) is it necessary to flush the brake fluid fluid every two years?
On the other hand, if a car is driven 20K miles a year, should the owner wait two years to perform the brake fluid flush? Considering the hygroscopic property of brake fluid, I have always flushed at two years even though the brake fluid had only been used for 7K miles. Am I wasting brake fluid? What are your thoughts on the subject?
 

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My take is that fluid is cheap. Calipers are expensive. I’d rather waste a little fluid to avoid the risk of a caliper seizing up.
 

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You can buy a % water meter. There are tables indicating boiling points vs % water for various fluids.

If you race you will want to flush the fluid more frequently. Heating the fluid increase the air pushed out of (during heating) and pulled into (during cooling) the system. This adds moisture. Additionally, racing heats to an extreme, and you really don't want to boil the fluid.

Two years is pretty much the max whether driving or not. Moisture not only creates lower boiling points, but can cause corrosion.
 

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You can buy a % water meter. There are tables indicating boiling points vs % water for various fluids.

If you race you will want to flush the fluid more frequently. Heating the fluid increase the air pushed out of (during heating) and pulled into (during cooling) the system. This adds moisture. Additionally, racing heats to an extreme, and you really don't want to boil the fluid.

Two years is pretty much the max whether driving or not. Moisture not only creates lower boiling points, but can cause corrosion.

Racing aside, most people out on the road do not replace at 2yr interval, at least here in the US. Brake fluid likely will not give you any indication of a problem, especially if you do not drive the car much. I am a recent culprit of lack of fluid change on a vehicle not often used. My main concern is corrosion, as Wayne mentioned above, need to be better about this. But realistically, a GLA250, can we do this every 3 yrs. I'd say probably fine, if your system has been closed, and you generally maintain the car, another 12 months likely not a big deal, probably doing better than 85% of the rest of the cars on the road.
 

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Brake fluid never used to be flushed. And every time a car came in for a brake job I needed to hone the cylinders (drum) or rebuild the pistons (disc).

Using my tool I find a water increase of about 1% per year. It is generally considered that 2% is about as high as you want to get. So two years is a good target in general.

But I agree that most would never know or see a difference going three or even four years.

Then again if you have a warranty issue it would be best to stay current.
 

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I have a good friend with whom I agree on most everything when it comers to proper vehicle maintenance, except this discussion. He never changes his brake fluid (which as you cite Wayne was the historical norm). He has had more caliper piston rebuild needs than have I.

I go with every 2-3 years. And as you have empirically shown brake fluid is indeed hydroscopic and therefore changing should be based on time and not mileage.

Brake fluid never used to be flushed. And every time a car came in for a brake job I needed to hone the cylinders (drum) or rebuild the pistons (disc).

Using my tool I find a water increase of about 1% per year. It is generally considered that 2% is about as high as you want to get. So two years is a good target in general.

But I agree that most would never know or see a difference going three or even four years.

Then again if you have a warranty issue it would be best to stay current.
 

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I just did the Service B on my 2015 GLA250. I also replaced the brake fluid based on the mileage. The brake bleeder kit I used made it a pretty simple one-person job. Pretty excited about the money I saved doing this myself.
What is the brake bleeder kit you used? What brake fluid did you use?

Thanks!
 

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Motul makes a great bleeder. You have two options ...

1. Fill the Motul bottle with fluid so the reservoir can't go dry. Just make sure the Motul doesn't go dry!!! You will need to clean the Motul Bleeder thoroughly when you're done or the brake fluid will eat the seals and the next time you use it you may leak brake fluid everywhere.

2. Use a turkey baster to empty the master cylinder reservoir. As you do this put the fluid into your bleed bottle. Make a mark on your bottle when the master cylinder is as empty as you can make it. Fill the master cylinder. Empty the catch bottle. Use the Motul Bleeder to pump air pressure into the master cylinder. Start bleeding the furthest brake from the master cylinder. Before you reach the mark on the bottle stop to fill the master and empty the bottle. Continue until all four corners are flushed.

In either case note how full the master cylinder is before doing anything. When you are done you will want the same level. The level lowers as your brake pads wear. If you fill the reservoir completely you may find it over flowing when you compress your calipers at your next brake job.

I'll head down to the garage and post pictures on a few minutes.
 

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I have the oil extracting unit as well. But when I used that I tested for how well it did by then putting the car up on the lift and draining any remaining oil from the plug. There was quite a bit of oil left to drain. I posted the results and they should be available on a search.
 

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Yessir, ol' school drain plug is still the best course of action, but now as a 'gentleman home mechanic' I must admit that I've gone for the easy/clean way in colder weather changes. Many dealerships now do top extraction as well, presumably to widen their profit margin.

I have the oil extracting unit as well. But when I used that I tested for how well it did by then putting the car up on the lift and draining any remaining oil from the plug. There was quite a bit of oil left to drain. I posted the results and they should be available on a search.
 

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Yep ... They will charge you for 6 quarts of oil but only need to use 4!!!

Oil changes are just dilutions. It's just a matter of degree.

My Porsche 997.2 holds almost 10 quarts but for 20 oil changes (5K mile intervals) I've drained 7.5 quarts and added the same. The other 2 plus quarts is held in the heat exchanger and plumbing.
 

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Sorry about previous post ... That's Motive Bleeder and Motul fluid.
How do you dispose of the used brake fluid?
 

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Put it into the bottles used to renew the system and take it to the local hazardous waste disposal.

Actually I have a bunch of leftover 5 gallon buckets from paint and joint compound. I dump oil and other fluids into those and haul them when I get enough full ones (20 gallon drop off limit at our center). I make 3 or 4 trips a year since I change oil and do other work for friends as well.
 

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Most of the chain automotive product stores will take/recycle used oil and brake fluid. However they typically won't take used coolant.
I just return the used fluids in the containers in which I bought the new product and/or in my drain pan which they kindly empty.

How do you dispose of the used brake fluid?
 

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Put it into the bottles used to renew the system and take it to the local hazardous waste disposal.

Actually I have a bunch of leftover 5 gallon buckets from paint and joint compound. I dump oil and other fluids into those and haul them when I get enough full ones (20 gallon drop off limit at our center). I make 3 or 4 trips a year since I change oil and do other work for friends as well.
Here the county recycling center will take automotive fluids only once a year.
 
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