Dot 5 Brake Fluid

[Mr. Man]

Ms.D and I went to a cruise-in this evening and whilst looking about at all the nice cars Ms. D came upon a truck that had purple parts. As she was examining all the purple goodies she noticed the brake fluid in the master cylinder was purple. "Must have" she exclaimed! So I meandered over to the owner and inquired about it. He said he got it at NAPA and that it was silicone based and was a DOT 5. My question to you all is....Is this kind of brake fluid compatible with the MM brake system and how much fluid does the system take, including any that may reside in the ABS?

Thanks for any help you guys may have:)

[fastblackmerc]

Ms.D and I went to a cruise-in this evening and whilst looking about at all the nice cars Ms. D came upon a truck that had purple parts. As she was examining all the purple goodies she noticed the brake fluid in the master cylinder was purple. "Must have" she exclaimed! So I meandered over to the owner and inquired about it. He said he got it at NAPA and that it was silicone based and was a DOT 5. My question to you all is....Is this kind of brake fluid compatible with the MM brake system and how much fluid does the system take, including any that may reside in the ABS?

Thanks for any help you guys may have:)

Do a google search, lots of info about DOT 5 and the pros & cons.

IMHO... it's not worth the hassle and potential problems.

[TAKEDOWN]

.... Oh boy! Lol, NOW she wants to match fluids. If I were you I'd keep a close eye on your wardrobe tOO Mr. Man!!!

[Brian H]

Dot 5 is a silicone based fluid. And WILL NOT blend with Dot 3!!!!! You MUST completely drain and flush any and ALL Dot 3 from your system for the dot5 to be used. YES, look up everything you can on this. Case in point, I switched over from Dot3 to Dot 5 on my bike and it gummed up my entire system. and guess what NO:eek::eek::eek::eek::eek: BRAKEEEEEEEEEEEEEESSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSS!!!!!!. And i would also like to note that the sole purpose of Dot 5 is Hi heat. It has a much higher boiling point than 3. So unless you autcross daily or run the slaloms daily its just not worth it.

[ctrlraven]

DOT4 or nada.

[Mr. Man]

Do any of the DOT 3/4 come in purple? Brands.....

[fastblackmerc]

Do any of the DOT 3/4 come in purple? Brands.....

No, DOT 5 is colored purple so you notice it and don't mix DOT 3 or 4 with it. If you do mix them you'll end up with crud in your brake system.

Paint your master cylinder.

[SpartaPerformance]

Dot 5 is a silicone based fluid. And WILL NOT blend with Dot 3!!!!! You MUST completely drain and flush any and ALL Dot 3 from your system for the dot5 to be used. YES, look up everything you can on this. Case in point, I switched over from Dot3 to Dot 5 on my bike and it gummed up my entire system. and guess what NO:eek::eek::eek::eek::eek: BRAKEEEEEEEEEEEEEESSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSS!!!!!!. And i would also like to note that the sole purpose of Dot 5 is Hi heat. It has a much higher boiling point than 3. So unless you autcross daily or run the slaloms daily its just not worth it.

They only way is to completely flush the system with mineral spirits for a loooooong time to get rid of the DOT 3, it's NOT worth the time or the risk. Sorry Ms.D

[GordonB]

Mr. Man/Eric,
We are NOT supposed to use DOT 5 in any ABS brake system, incl. our MMs.
Main benefit with DOT 5 is superior long-term durability and almost no hydroscopic qualities. It's great for an older, non-ABS car brake system. Just run some denatured alcohol thru the system to get rid of the remaining glycol (standard DOT 3/4) brake fluid.
Many people with MMs use Royal Purple but I don't know the color or where to buy.
I have been running Valvoline DOT 4 synthetic in both MMs for the past 2 brake flushes, incl. this past April for both. You will need 1 quart of fluid and maybe an extra pint for the MM. If you were closer to me, I could use the vacuum 'suck system' at each wheel or the newly acquired pressure tank that 'pushes' the fluid out from the master cylinder to each wheel.
PM me if I can help you.
GordonB

[Mr. Man]

Well upon further research I am going to throw the towel in on the DOT 5 brake fluid. Looks like DOT 4 is going in when the system is done. Anybody have any thoughts on the DOT 5.1? Our thought for the DOT 5 was purely aesthetic not a heat related or water issue. Thanks to everyone for their thoughts and advice.

[fastblackmerc]

Well upon further research I am going to throw the towel in on the DOT 5 brake fluid. Looks like DOT 4 is going in when the system is done. Anybody have any thoughts on the DOT 5.1? Our thought for the DOT 5 was purely aesthetic not a heat related or water issue. Thanks to everyone for their thoughts and advice.

Just stick with DOT 4.

Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F)
DOT 5.1 270 °C (518 °F) 190 °C (374 °F)

As you can see DOT5.1 has a higher boiling point but unless you get all the DOT 4 out the DOT 5.1 will be degraded.

[Mr. Man]

Just stick with DOT 4.

Dry boiling point Wet boiling point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F)
DOT 5.1 270 °C (518 °F) 190 °C (374 °F)

As you can see DOT5.1 has a higher boiling point but unless you get all the DOT 4 out the DOT 5.1 will be degraded.

I saw this same chart too. We don't do any autocrossing and although Ms.D drives it like she stole it, I don't think she is getting any heat issues so DOT 4 it will be.:beer:

[GordonB]

Eric,
I re-read your post and realized that you were actually talking about DOT 5.1, non-silicone, brake fluid.
If you have never flushed your brake lines, consider running some denatured alcohol thru them as a 'chaser' before putting new brake fluid in them.
GordonB

[fastblackmerc]

Eric,
I re-read your post and realized that you were actually talking about DOT 5.1, non-silicone, brake fluid.
If you have never flushed your brake lines, consider running some denatured alcohol thru them as a 'chaser' before putting new brake fluid in them.
GordonB

No, he was talking about DOT 5.

"He said he got it at NAPA and that it was silicone based and was a DOT 5."

[Mr. Man]

Eric,
I re-read your post and realized that you were actually talking about DOT 5.1, non-silicone, brake fluid.
If you have never flushed your brake lines, consider running some denatured alcohol thru them as a 'chaser' before putting new brake fluid in them.
GordonB

I was initially asking about the silicone based DOT 5 but then I asked about the DOT 5.1 and if anyone had used it and what were their impressions.
We will most likely go with the DOT4 when it's time but the DOT 5 has advantages that the glycol based stuff doesn't. The car sits outside all year and the driveway is stones so there is constant moisture, though a bit less in the winter as humidity levels are a tad lower. Cleaning the lines, master cylinder and calipers are not an issue but I'm not all that familiar with the ABS. Is there a reservoir in the ABS that would need to be flushed.

[fastblackmerc]

I was initially asking about the silicone based DOT 5 but then I asked about the DOT 5.1 and if anyone had used it and what were their impressions.
We will most likely go with the DOT4 when it's time but the DOT 5 has advantages that the glycol based stuff doesn't. The car sits outside all year and the driveway is stones so there is constant moisture, though a bit less in the winter as humidity levels are a tad lower. Cleaning the lines, master cylinder and calipers are not an issue but I'm not all that familiar with the ABS. Is there a reservoir in the ABS that would need to be flushed.

No reservoir for the ABS, just the reservoir on the master cylinder. Probably a job for a professional with the right equipment as you don't want to get any air bubbles in the ABS controller.