Dot 5.1 brake fluid

[Fudd]

Can Dot 5.1 brake fluid be used as a replacement for Dot 4 (after flushing) in a Valkyrie?  I've heard both good and bad things about it.  While there is less danger of ruining your paint job from accidental contact, contaminents in the system can cause the fluid to jellify.  At least that's what I've heard.

Anybody got a feel for this?

[Patrick]

Just my opinion, put in the same as you took out..

[Patrick]

Just my opinion, put in the same as you took out..

[9Ball]

I believe you're confusing DOT 5.0, which is NOT compatible with DOT 3/4 and will cause the problems you've heard of.  A quick internet search should tell you compatibility of 5.1 with DOT 3, 4, or 5.0, but I believe it is compatible with 3 and 4.  Don't hold me to it.

I would stick to DOT 3/4 synthetic....can be mixed with regular DOT 3 or 4 and has a bit higher boiling point.  Valvoline Synpower (or their latest incarnation) is good stuff, available at most big chain auto stores.  It now comes in pint size so you don't have to buy the quart and throw a lot away.  Once the container is opened, you should not store it for long periods.

[Ricky-D]

A complete clean out would not put you in a better change out condition because the problem is with the seals and O-rings being compatible with the different brake fluids.

Some fluids are like solvents when exposing the sealing parts to these fluids.

***

[Robert]

5.1 is fully compatible with 3 and 4, just make sure its not the silicone 5.0 thats not compatible. The higher boiling point is always a advantage.

[BonS]

  What Robert said.

Dot 4 and Dot 5.1 are just more refined versions of the same basic Dot 3 fluid. The improved refinement does indeed give them a higher boiling point. I think it's really lame to name Dot 5 and Dot 5.1 so similarly. It's just bound to have some poor folks contaminating their brake systems. 

[98valk]

all brake fluid is synthetic. 5.1 is for modern ABS systems, different viscocity, which will not be perfect for a DOT 4 system. 5.1 is same chemicals as DOT 3/4 and same paint eating ability. DOT 5 is silicon fluid, expensive only good for race track use and vehicles that sit for yrs.
 ATE is the best DOT 4 brake fluid for street use u can get at a reasonable price. some can argue motul, wildwood, $$$ etc. ATE is in a metal can, others in plastic. It has been tested that brake fluid absorbs moisture in the air right thru the plastic bottles while sitting on the shelf lowering the wet point listed on the bottle, in metal it cannot.

http://www.raceshopper.com/ate_brake_fluid.shtml  This is also the lowest price u can get.

 U will only have to change it out every 5 yrs maybe longer it using braided hose, the teflon liners lets less moisture in than rubber hose, instead of 2-3 yrs as with common DOT 4. Using the old syn power which had a higher wet point than regular DOT 4 and braided hose, my fluid started changing colors after 9 yrs, replaced it after 10yrs. when a brake fluid starts turning dark it is because of moisture intrusion. Always get the highest wet boiling point which will last the longest in a street vehicle. Dry boiling point has to do with racing use.

http://www.afcoracing.com/tech_pages/fluid.shtml
http://www.stealth316.com/2-brakefluid.htm
http://www.timskelton.com/lightning/race_prep/brakes/brake_fluid.htm
http://www.aa1car.com/library/bfluid1k.pdf
http://www.centricparts.com/files/Centric%20White%20Paper%20D1-Brake%20Fluid%201A.pdf

[Fudd]

A complete clean out would not put you in a better change out condition because the problem is with the seals and O-rings being compatible with the different brake fluids.

Some fluids are like solvents when exposing the sealing parts to these fluids.

***

I'm not buying this argument.  I can't find anything that says 5.1 is not compatible in a Dot 4 system, but I'm always willing to learn.  Where did you get your information that it was incompatible?

I live in an area of the country that generally has as much as 100% humidity.  Brake fluid contaminates quickly and turns brown quickly here.  I like to change brake fluid every three years, or so.  I typically flush with an unused but opened can that was left from last time.  I know, it has a little color to it, but looks way better than whats in the reservoir. I then put new fluid in it.

A Harley old timer is the guy who first told me about "5.1."  He changes brake fluid more often than I do.  He tells a story about moisture contaminated fluid boiling, making bubbles in the line and leaving him with almost no brakes.  He claimes 5.1 works fine for him and he says it doesn't destroy paint with incidential contact.

I didn't know it was a different viscocity.  I guess I will stick with the Dot 4 because of my fears of the unkown, when I do my next change.

[bentwrench]

DOT4 is cheap,valk fluids are easy to change.I push fresh fluid thru both brks and clutch every fall.That way any sitting it does during the winter will be in new fluid.Been doing this with all my bikes for 30 years and i've had no caliper or M/C problems.bikes that sit with old fluid in them are the ones that develop pitting and seal problems.I've seen some real ugly brake parts over the years,enough to keep mine in clean fluid.Your brakes ain't the place to scrimp.
BW

[Farther]

I don't know if this has been cited yet but it deserves a repeat if it did.
http://www.xs11.com/xs11-info/tech-tips/maintenance/brakes/23-the-great-dot-brake-fluid-controversy.html

[T.P.]

I have used 5.1 for years without any problems.

http://en.wikipedia.org/wiki/DOT_5.1