Is it true that the Valvoline Synpower brake fluid is not as good as some of the pricier brake fluids such as Motul, ATE, etc. when it comes to compressibility? I've read and heard that some people dislike the Valvoline because it tends to give a mushier pedal feel than the other fluids out there. I switched over to a front Stoptech 13" kit at the beginning of this year for track duty. I've always used the Valvoline fluid. The car stops fine and the pedal travel is decent but the pedal just doesn't feel rock hard as it should be. When moving if I apply the brakes normally with one pump it will travel a certain reasonable distance and then hit the solid point. If I tap the pedal real slightly once (without engaging the brakes) and then immediately apply the brake again the pedal travel is significantly shortened and feels rock solid. This is how I want the pedal to function without having to do the two pump method. Assuming the brakes have been bled properly and there is no air in the system, would switching over to something like Motul RBF 600 make a noticable difference in pedal feel?

 

Almost all fluids are incompressible, so one fluid can't really be "mushier" than another. Mushy feelings are usually associated with air in the lines, not with the specific fluids

 

I've been using Synpower for over a year now and never noticed any problems with pedal feel. It doesn't have the temperature range of the Motul or ATE fluids, but it's not as expensive either. For everyday use, autocrossing and the occasional HPDE it's done fine for me.

I'd have to agree with redlude, it's probably an air bubble in the system, not the fluid.

 

I really hate the Valvoline stuff.

I'm not sure what it is, but it does feel mushier. And no, there were no air bubble in my system the few times I tried that fluid.

I think it's a question of fluid viscosity. Q45 was hinting at that property in a previous topic, and it's effect on pedal feel.

I use RGS610 fluid (http://www.renugroupllc.com/rgs610/product_page.htm) in my car. It's quite expensive (~20-25$ a pint) but very stable. Even bellow freezing, the pedal feel remains constant. Plus it's dry boiling point is the highest I've seen and the wet boiling point is also very high. I'm not using anything else from now on.

The Motul 5.1 fluid was nice too. Better than the Valvoline stuff IMO.

Tapping the brake pedal will always reduce the pedal travel. Only when you have brand new pads will you get a "stiff from the start" feeling. it's not related to the fluid, it's simply that the first tap will pump fluid in the caliper, bringing the pads closer to the rotor.

 

Thanks for replies guys. Kolia, your explanation make sense. My HPS pads in the rear are actually pretty low at I would say 20% or less remaining. The Axxis Ultimates in the front have a lot of material. I'm sure when the time comes to replace the rear pads I will notice a difference since there won't be so much room for the piston to travel.

 

i just went from the vavoline to motul. I really can't tell the difference in feel. vavoline worked just fine.

 

I've never noticed a difference either, going from the very expensive Castrol SRF to Valvoline.

I now just run the ATE superblue, and it also works just fine, zero issues

sounds like you absolutely have air in the system if you have to pump it up more than once to get a harder pedal, or your master is beginning to die slowly

 

What kind of test could I do or what do I look for to see if the master cylinder is bad? I push the pedal all teh way down and hold it for 30 seconds and the pedal does not move anymore so there isn't a leak. I've checked all the bleeder screws, lines, etc. and everything is fine. But I've heard that sometimes seals internally in the master cylinder could be bad so it lets fluid go by.

I really don't think it's air in the system because I've bleed this thing to death already. First time I used speed bleeder screws. Those sucked literally and had all kinds of air in the calipers. So I did it the good old two man way and that helped out tremendously. Third time later on used the Motive power bleeder and that got out maybe a couple of more bubbles.

I guess what I should be really asking is how much range of pedal travel is normal before the pedal hits the solid point? Maybe I'm jsut being too picky with what I think should be normal.

 

Quick question, is this the one to buy?
Dot 3 and Dot 4?

 

That's the right one, just be sure to check the expiration date.

 

usually the MC will get a bit "wet" around if it starts to leak. Car also tends to lose vacuum too, so you can check that at any vac source, like the intake manifold

bleeder screws I'll agree with you...they suck lol

pedal feel will really vary based on your pad and the caliper itself.

Was the pedal feel ever good with your current brake setup and has gotten worse?

 

Those are the old bottles, they have a newer design on the front now, probably better to look for some of the newer bottles if possible

 

Well right now I'm running Stoptech 13" with Axxis Ultimates in front. Rear is stock with HPS pads that are getting on the thin side. The feel isn't bad and mushy like before when I had lots of air from the speed bleeder screws. But I think there is still room for improvement. Like I said maybe I'm just being too picky and expecting too much. I'll change out the rear pads soon and see what that does. I'll also inspect my MC.

 

I run Motul RBF600. It works fine for me. The benefit is not that it gives better pedal feel, it's that it has pretty much the highest dry (593*F) and wet (420*F) boiling points of any DOT 4 fluid around (disclaimer - I'll bet there's something else, but I'm unaware of it).

 

The Motul is a great product.
The RGS610 from my previous post is rated at 610F dry and 421F Wet.

The viscosity rating is also very nice.

 

When I drove your car it felt good to me. Has it changed since? I think that our Nissans do not have the best pedal feel. Compared to a bimmer or porsche for example, our brake system just does not have the same feedback or confidence. Stopping power is there, just not the direct feel you get with a premium sports car. I feel the same way about the steering..

 

i use valvoline syncpower on all four of my cars. Great fluid no issues to date!

 

Dave, like I mentioned earlier it probably is just me being picky. It's still the same as the last time you bled it for me. You hit it on the head saying the stopping power is there for sure, just not the direct feel. And your're right about the bimmer. Drove an '02 330ci 5spd once and the brakes felt firm and direct. I'm probably also spoiled with driving an EVO 8 with Stoptechs as well. I guess I'll stop obsessing about this now and accept it for what it is.