(’14-’18) 2015 Forester brake fluid flush – subaru forester owners forum fluid buildup in ear

First of all, thanks to forkster for the link to the Maintenance Schedule. I’ve printed that to keep it in my service record file. Much easier to access that, than go hunting for the owner’s manual in the wife’s car! I would like to point out to both you and Scooby that those recommended intervals are in kilometres, not miles – big difference. I would also point out that ALL brake fluid is a synthetic product. It does not occur naturally. There is nothing special about the brake fluid in a Subaru and I was surprised to see they install DOT 3 in them, rather than the superior (for boiling point) DOT 4.

Referring to the Maintenance Schedule, you will note they also state a time frame for these services. Time can be much more important than mileage, especially when it comes to brake fluid, for, as was pointed out already, water absorption over time will deteriorate the fluid . . .

even if the car goes nowhere! I found this quote from forkster to be quite uninformed on the subject of brake fluid – Considering the fluid is 100% synthetic, it should last at least 100’000+ miles or if it get completely dark brown before you need to even consider changing the fluid.

No one told me to replace the fluid, but the car is approaching three years old, as in the 36 months recommended for the ‘C’ level of service, which includes the brake fluid. I had planned to do this flush while I was taking the snow tires off this year. The fluid colour right now is a medium yellow, at 20,000 km. and I find it extremely difficult to believe that forkster’s fluid is still as clear as water, with no discolouration at all after the same approximate length of time as on our Forester, although, we live on Canada’s wet coast, with a much more humid climate, so . . . maybe Calgary is a lot drier.

In all my cars and motorcycles, over the years, I have routinely changed brake fluids every two, or three years at most. Letting the fluid get to dark brown is rather foolish, IMHO, as it is well contaminated by then and corrosion damage to piston bores is likely well underway. Frequent changes, within factory stated limits, will greatly improve the chances of not replacing calipers for a long time. My previous 2001 Accord did 275,000 km and 14 years before I needed to replace just the rear wheel calipers and at that point, only one was partially seized.

So after all that, the reason I came here first of all was to query the weird (to my previous experiences) dual compartment master cylinder reservoir, which I wanted to drain before adding new fluid and then bleeding. The most logical explanation that I found elsewhere, (but not actually verified), is that this is merely a safety feature that Subaru employs to protect against total loss of braking, should a leak at one wheel in the system occur. Each section of the reservoir supplies two wheels, front and back, so a leak in the front system will not affect rear wheel braking. Sounds reasonable, but doesn’t change the fact that it makes a bleed more time consuming, as one needs to first bleed out the reservoir from two wheels, before you can refill the reservoir with new fluid, to do the full four wheel flush.

I use a Motive pressure bleeder system to power flush and bleed the brake fluid on all of them with the proper master cylinder cap. It’s a pain free 15 minute job on any car I’ve done it do so long as you can easily get to the bleeder screws, most trucks and suv’s I don’t need to even lift the wheel to get the brake line wrench and drain tube onto the bleeders. My 90’s fords actually had bleeder screws on the master cylinder for each compartment, which I would flush out first before doing the wheel cylinders when I flushed the fluid in my `97 cobra and `96 explorer.

My general brake fluid flush schedule for a daily driver is every 2-3 years, for my track car it’s once a year or if I have a fluid boiling event at a track day. It’s extremely cheap and easy insurance once you have the pressure bleeder system and it’s about the length of time I’m comfortable with going between inspections of my brakes and suspension bushings anyways.

Appreciate the reply and your experience. You seem to have had much more use for a pressure system than I ever would, so I can’t rationalize buying that for our two cars that I only do every two to three years. As to the reservoir, I’ve always had Honda vehicles, with normal (to me) reservoirs and the wife’s Subaru was my first time doing this service for her, hence my surprise at what I found.

As I mentioned in my previous post, I was going to bleed the system while I was changing out the snows, but with your comment about not even lifting a wheel, I will check out how easy the bleeders can be accessed without raising, or removing, the wheels. Cheers!