Safe to use DOT 5.1?

[mechaghost]

Is it safe to use Motul DOT 5.1 on the BRZ/FRS? I'm looking at this one: [ame="http://www.amazon.com/gp/product/B004LF1U40/ref=oh_details_o00_s00_i00"]Amazon.com: Motul 3364HL Dot 5.1 100 Percent Synthetic Non-Silicone Base Long Life Brake Fluid - 500 ml: Automotive[/ame]

Also, how much should I be buying? I'm planning to replace all the brake fluids.


Thanks!

[Matt Andrews]

yes, its safe. Why are you replacing what comes from the factory out of curiosity? You planning on tracking the car? If so, I'd go with the 600. If not, then I don't see why you'd need to change it?

1 bottle should replace the whole system...which you would want to do instead of simply topping off the stock fluid with this.

[mechaghost]

I'm switching it out because of the occasional track use and moderate autox. Plus I am changing out the brake lines as part of the stoptech brake kit

[NESW20]

have you already tracked the car and found the OEM brakes to be insufficient for you? have you tried simply upgrading the pads?

i second the rbf600 instead of the 5.1 for track and autocross duty.

[dave99rt]

you might want to check the specs on that fluid.
i'm pretty sure all the newer dot 4 race fluids have higher boiling points.

[BaBaFlyingSheep]

Originally Posted by mechaghost

I'm switching it out because of the occasional track use and moderate autox. Plus I am changing out the brake lines as part of the stoptech brake kit

Necro-thread but can't seem to find any other thread with DOT 5.1 in the title.

Did you end up switching to Motul 5.1, and was everything working fine?

I seem to have a hard time on really specific information on the web, but here's to summarize the main points. I'm sure everyone already knows the common knowledge, but I know people will restate it anyways.

Boiling point wise, dry and wet, in general (or by standard), DOT 3 < DOT 4 < DOT 5 = DOT 5.1.

We get some DOT 4 that's superior in boil temps than DOT 5.1, but it's not considered a DOT 5.1 due to it's higher viscosity.

With that said, viscosity: DOT 5 = DOT 5.1 < DOT 3 < DOT 4.
Sometimes, DOT 4, due to it's high viscosity runs into problems on certain systems, but the viscosity lowers at high temps, so it's usually fine for tracking, from what I gathered it because it's more "track-orientated" and the high temp lowers the viscosity for better operation. (I'm assuming this because, why not just call the DOT 4 a DOT 5.1 if it's got some high boil temp resistance)

Now here's why I'm asking if DOT 5.1 was ok for your brake system. As we all know, and I'm sure someone will state it, DOT 5 is silicone-based on not compatible with the other specs, there's also a lot of other reasons DOT 5 is not recommended, but I won't get into details. We do know it's usually used on older cars without ABS systems.

The reason is that the low visc messes with the ABS.
Now, DOT 5 and DOT 5.1 have the standards, visc. and boil temps, the only differentiating factor is silicone-based or not.

With that said, will DOT 5.1 screw up our ABS systems because it has similar visc specs as DOT 5?
Motul 5.1 claims it's "designed for ABS" systems, but is it meant for systems that can handle low visc?

I'm looking looking at the owner's manual and it DOES NOT state DOT 5.1, only DOT 3 or 4, FMVSS 116.

Even if the stock ABS system can handle the low viscosity of 5.1, does this void the warranty?

I was considering Motul 5.1 because it seems to have the best overall bang for your buck on performance & longevity.

[ryoma]

if the owners manual states to only use DOT 3 or 4, then stick with that. you won't even have to change out your brake fluid often with normal driving. if you're going to frequent the track, then no matter what fluid you're getting it will be changed out often due to the harsher conditions.

bottom line, don't cheap out on anything that will save your life. I personally am using Torque RT700 and that is expensive, but great results to justify the price in my eyes. RBF600 is great for the money as well.