Gen IV Brake Fluid Type?
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Yes, I flushed our old '10MY Outback with this very product. Also, my brother's '06MY Impreza with no problems what-so-ever. BTW all brake fluid is synthetic.Guess it is the same as last Gen. Thanks.
Is anyone using the Valvoline Synthetic DOT 3 and 4?
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2015 OB Limited 2.5i PZEV MR, Keyless Access & Push-Button Start, Nav, Eyesight - Tungsten Metallic
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This note in the OB owner's manual puzzles me:
"Avoid mixing DOT 3 and DOT 4 brake fluids even if they are the same brand."
If DOT 3 is adequate then what harm could there be by adding a DOT 4?
Also, what comes from the factory? Seems the only "authorized" fluid that can be used to top off the reservoir would be what Subaru sells through the dealer's parts department.
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"Avoid mixing DOT 3 and DOT 4 brake fluids even if they are the same brand."
If DOT 3 is adequate then what harm could there be by adding a DOT 4?
Also, what comes from the factory? Seems the only "authorized" fluid that can be used to top off the reservoir would be what Subaru sells through the dealer's parts department.
I have flushed the brake system with the valvoline synthetic fluid with no problems and have been running it for the last 5k or so without a problem.
Brake fluids are generally not advisable to mix because of boiling point differences in the fluids. If you mix a lower boiling point in with a higher one and for some (ungodly) reason manage to actually heat your fluid up that much you will boil the lower fluid while maintaining the upper fluid. And if anyone has seen boiling water and oil mixed together, this is a recipe for disaster. Also, different brands may use different additives/formulations to reach the listed boiling point, and may not be compatible.
My general take is that if you are going to work on the brakes, bleed the whole system through the drain plugs (having a helper man the pedal makes life a lot easier) and always refill with a single fluid type...whatever your choice may be.
Brake fluids are generally not advisable to mix because of boiling point differences in the fluids. If you mix a lower boiling point in with a higher one and for some (ungodly) reason manage to actually heat your fluid up that much you will boil the lower fluid while maintaining the upper fluid. And if anyone has seen boiling water and oil mixed together, this is a recipe for disaster. Also, different brands may use different additives/formulations to reach the listed boiling point, and may not be compatible.
My general take is that if you are going to work on the brakes, bleed the whole system through the drain plugs (having a helper man the pedal makes life a lot easier) and always refill with a single fluid type...whatever your choice may be.
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The recommendation would be to use Dot 4 because of the higher boiling point and then use something like Prestone synthetic which indicates on the bottle it can be used with any brand or any type either Dot 3 or Dot 4. Case closed. And it's literally absurd to think that you couldn't mix any brand together any dots together if you think you'd run into a problem I dare you to show me. It wouldn't happen. But it is better to just go with a bottle that confirms it's fine and don't worry about it. But like others have pointed out Common Sense would say it would not matter. If you take your car to an oil change shop they have no clue what type/brand of fluid you have in there and they're going to top it off with whatever they have. End of story. Don't be sheep and follow manufacturer's suggestions that are going to have you with your tail between your legs running back to them for help.This note in the OB owner's manual puzzles me:
"Avoid mixing DOT 3 and DOT 4 brake fluids even if they are the same brand."
If DOT 3 is adequate then what harm could there be by adding a DOT 4?
Also, what comes from the factory? Seems the only "authorized" fluid that can be used to top off the reservoir would be what Subaru sells through the dealer's parts department.
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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '12 Mazda3 skyactive
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The boiling point between the two is almost a non issue. If you look at most mid grade brake fluids they all have a higher than spec wet and dry boiling point. Meaning you can run a DOT3 with a higher BP than a DOT4.
If subaru says you can use either 3 or 4 then go with what ever is cheaper with a higher wet and dry BP. However some vehicles state dot 3 only. Technically a 4 can be used but in rare cases it may not be compatible with certain metals in the brake system and lead to corrosion over time.
My Toyota specs DOT3 only but I use a top grade DOT 3 fluid that has a much higher BP than DOT 4 fluid and has never boiled on the track.
Realistically none of us will ever come close to boiling our fluid dailying our cars. Only exception might be those who live in mountainous areas and tow. Even then, if your fluid is flushed every couple years so it is always dry then you should have no issues.
If subaru says you can use either 3 or 4 then go with what ever is cheaper with a higher wet and dry BP. However some vehicles state dot 3 only. Technically a 4 can be used but in rare cases it may not be compatible with certain metals in the brake system and lead to corrosion over time.
My Toyota specs DOT3 only but I use a top grade DOT 3 fluid that has a much higher BP than DOT 4 fluid and has never boiled on the track.
Realistically none of us will ever come close to boiling our fluid dailying our cars. Only exception might be those who live in mountainous areas and tow. Even then, if your fluid is flushed every couple years so it is always dry then you should have no issues.
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