13 replies to this topic

[Sphinx]

So, it looks like Valvoline is updating their line.  My local Autozone clearanced them out for 97 cents a bottle, and I didn't get a single one.  None of my local stores are carrying anything other than house brands, except for Pentosin - German brand, never heard of it - anyone use it?

 

They carry two flavors, a Super Dot 4 and a Dot 4 LV (low viscosity).  I also noticed that Ford stuff is now available in a new DOT 4 LV flavor too.

 

So, what's with the LV stuff?  Anyone using it?  Good/bad?  And any suggestions for other brands till my stores stock up again?

[EricJ]

Per the chart, Prestone looks to have a little better specs than Valvoline, as good as Castrol, and is a little cheaper.

 

https://www.lelandwe...rison-chart.cfm

[OrangeCrush86]

You can get the better quality Castrol stuff on Amazon.

[manthony121]

I have not heard of "low viscosity" brake fluid before.  As brake fluid doesn't really flow anywhere, it doesn't seem viscosity would be nearly as important as it's boiling point, etc.

[Dave D.]

The low viscosity fluid is for modern cars with very sensitive ABS/Trac/stability control. It needs to flow through the very tiny passages and valves quickly.

[Justin Casey]

I've never heard of the low viscosity brake fluid before.

 

I also recommend exploring other options off good ol' Amazon. (Might save a few bucks)

 

I've always used Motul RBF600 without any issues (594F dry boiling point/ 401F wet boiling point).

https://www.amazon.c...ds=motul rbf600

 

Castrol SRF is also a popular choice.

https://www.amazon.c...ds=castrol srf 

[davew]

SRF is way overkill for a Miata. $65 per liter!! I use it in the Trans Am cars and in the Global Cup cars.

 

Castrol GT/LMA is what we use in all our SM's

 

dave

[Sphinx]

I noticed that Redline has also introduced a brake fluid - anyone try it?

 

BTW, I recently experienced boiled fluid with the Valvoline.  Not sure why, though it had been a couple of HPDE events at Sonoma since I'd bled the brakes.  First session at Laguna and minimal pedal.  Good enough to get through the session and then I bled it and it came back (mostly).  As slow as I am, I'm surprised that I boiled the fluid.

[SaulSpeedwell]

My $0.02 on brake fluid:
 

1.  I never "boiled" fluid on an SM, even with 1.6 brakes.  The lowest spec fluids I used were FoMoCo HD DOT 3, Castrol LMA, and what was once Valvoline SynPower DOT4.

 

2.  Unless you bleed every couple of weeks, and only use fluid from sealed unopened containers, you should assume you are at the fluid's "Wet" boiling point.  Pegasus probably still publishes the chart all in one place.

 

3. Thought experiment:  When you bleed fluid on a street-type SM caliper with both the brake line and the bleeder on the top, are you actually removing all the fluid from the bottom 50/80/95% of the caliper?  My vote is no.  I spent a lot of time with the dyed brake fluid convincing myself of this.  On an initial build, or annually, I would do something better than just traditional "bleeding".  Vacuum bleed from the top, or dump out the calipers, or something.  

 

4.  I can't tell if all the clutch slave cylinders suck these days, or if something was magic about Mazda's OEM fluid, or if the clutch slaves get killed by high-spec brake fluids.  In any case, I have gone back to using garden-variety DOT3 in Miata clutch slaves for both street and race, and life has improved ... but nowhere near the true original's life.  I seemed to kill clutch slave cylnders fast and furiously, both street and race, once I started putting DOT4 race-spec fluid in the clutch hydraulics.  What has everyone else experienced?

[ChrisA]

^ #4 - I have used Motul RFB600 most of the cars life (bought it new) and I’m still on the original master & slave cyl. - knock wood.

[LarryKing]

 

I never "boiled" fluid on an SM, even with 1.6 brakes.

That because you never slowed down much.

[wheel]

Granted, SM does not use the brakes like American Sedan, but I have had great success in the Firebird with the Wilwood EXP.  Pretty good price for the numbers.

[Steve Scheifler]

I noticed that Redline has also introduced a brake fluid - anyone try it?

BTW, I recently experienced boiled fluid with the Valvoline. Not sure why, though it had been a couple of HPDE events at Sonoma since I'd bled the brakes. First session at Laguna and minimal pedal. Good enough to get through the session and then I bled it and it came back (mostly). As slow as I am, I'm surprised that I boiled the fluid.

You may be mistaking one of several things for boiling fluid. In an SM I’ve turned the edges of hawk blues to ash and completely burned the material off Carbotechs without boiling Valvoline fluid. More importantly, when you do actually boil the fluid you very abruptly have zero pedal from that end.

Mark, I’ve wondered the same thing about purging fluid from calipers but never having had problems related to it I haven’t put much effort into finding out. However, with new pads the pistons are far enough back that I expect with enough repetitions the turbulence and flow mixes up the rest enough to do a pretty good job. If I were worried about it I would keep a stack of shims or the like to keep the pistons back during bleeding, even with thin pads.

And speaking of lots of repetitions when bleeding, related to your comment about dry vs wet, as I’ve said each time this comes up, that’s why we use Valvoline. I could get it anywhere, cheap, and never feel bad about frequent and thorough bleeding. I’d rather have a fresh batch of it in my car and plenty more in the trailer than worry about the cost of each pump when using stuff that’s 10x as expensive, not readily available in a pinch, and only marginally better wet.

[FTodaro]

^ #4 - I have used Motul RFB600 most of the cars life (bought it new) and I’m still on the original master & slave cyl. - knock wood.

Me too exactly Motul all around no failures