synthetic brake fluid

[nis350]

is synthetic dot 3 & 4 brake fluid compatible with the regular dot 3 an 4 fluid? OK to mix?

 

[NSX-Racer]

Isn't brake fluid always synthetic?

 

[Larry Bastanza]

I thought DOT5 was the only synthetic. But if DOT3/4 is now available in synthetic the answer is no it cannot be mixed, based on the cautions of mixing DOT5 with any DOT3/4.

I think some further investigation is warranted on this topic.

NOTE: After a little investigation it is clear I have no idea what I am talking about. It appears that DOT5 is silicone based which will not mix. The ATE Blue/Gold which I have been using for years is synthetic and compatible with DOT3/4 fluids.

HTH,
LarryB

 

[NSX-Racer]

I did some research too, Larry, and it turned out that you can mix any DOT 3,4, 4+ and 5.1 fluids - it's not really recommended to mix different fluids but it will do no harm. But - as you wrote: You can't mix any of them with DOT 5 (something else as 5.1). If a brake system is marked as DOT 5 required you can't use other than that fluid.

Some recommend 5.1 for brake systems with ABS because it has lower viscosity so that the ABS could react quicker and it should be easier to get air pockets out of the system (bleeding). Not my statement but if that is really true it seems that DOT 5.1 is a good advice for the NSX.

And: My former question should be answered "yes" - brake fluids are a synthetic product made of mineral oil as basic - mainly with polyglycol, polyglycoleter or (in the case of DOT 5) silicone.

 

[nsxtasy]

is synthetic dot 3 & 4 brake fluid compatible with the regular dot 3 an 4 fluid? OK to mix?

I think you're confusing the term "synthetic" with "silicone".

As noted above, DOT 3, DOT 4, and DOT 5.1 brake fluids are glycol based (NOT silicone based) and can be mixed with each other with no problems. DOT 5 brake fluid is silicone based and cannot be mixed with any of the other DOT designations.

Some recommend 5.1 for brake systems with ABS because it has lower viscosity so that the ABS could react quicker and it should be easier to get air pockets out of the system (bleeding).

The main advantage of DOT 5.1 is that it has higher minimum required boiling temperatures than DOT 3 or DOT 4, which means that it is more resistant to fluid boiling and resulting brake fade. However, you can get fluids such as Motul RBF600 that meet the boiling point minimums of DOT 5.1 but are classified as DOT 4.

 

[Larry Bastanza]

Hi Ken,

Actually I think the only one confused was me LOL........................

LarryB

 

[NSX-Racer]

Ken, as you didn't include in your quote but as I wrote, it was not my statement. I read this in the customer's information of companies like rockoil, synlube and Motul. Of course the higher boiling point of 5.1 is advertised too.

All in all it seems that 5.1 would be a good choice for us weekend warriors with the NSX.

 

[nis350]

NOTE: After a little investigation it is clear I have no idea what I am talking about. It appears that DOT5 is silicone based which will not mix. The ATE Blue/Gold which I have been using for years is synthetic and compatible with DOT3/4 fluids.

HTH,
LarryB

Thanks Larry, I was shopping for brake fluid and noticed some label as synthetic dot 3 & 4 and others do not have the 'synthetic' label. Not sure if all dot 3 & 4 are the same.

 

[nsxtasy]

I was shopping for brake fluid and noticed some label as synthetic dot 3 & 4 and others do not have the 'synthetic' label. Not sure if all dot 3 & 4 are the same.

You can mix any DOT 3, DOT 4, or DOT 5.1 brake fluid with any other DOT 3, DOT 4, or DOT 5.1 brake fluid - regardless of whether or not it says that it's synthetic on the label.

So the answers to your two original questions are yes and yes.