Dot 5 mixing

[Splangj]

I’ve read RE’s articles about all subjects. I’m pretty sure he said we can mix dot 4 and 5 with no issues. I don’t know if he actually did that, but I’m thinking about it. It’s actually on my motorcycles front disc assembly. The master leaked, and the dot 4 ruined the whole thing. It stops well but is a mess. Yamaha doesn’t sell the master any longer, so I bought one from Amazon. It’s given five stars and fits well. It also says Dot 4 fluid only. AND it was $19, go figure. I’d rather not purge the whole system if I don’t have to.

 

[Cranky]

From what I understand, you should never use DOT 5 in a system that was designed for 3 or 4.....

 

[DeltaV]

This sums up what I've always heard:

DOT3 and DOT4 should never be mixed with DOT5 fluid. They're incompatible, and brake failure may occur if mixed. Moreover, there are serious compatibility issues when using DOT5 in a system that was engineered to use DOT3 or DOT4. Also, users should take care not to mix DOT3 and DOT4 fluids as there could be brake system compatibility issues. Always consult your owner’s manual and use the type of fluid specified for your vehicle.

Source:
Know the Difference Between DOT3, DOT4 and DOT5 Brake Fluid.

 

[Kern Dog]

If Rick Ehrenberg uses it in classic cars, I'd trust it.
I have DOT 5 in my car. I did not mix it with anything. I wouldn't risk that.
Some claim it gives a mushy pedal. That hasn't been the case for me. I've finally got my brakes to a point where I have total confidence in them.
I decided to use it simply for the paint protection. DOT 5 is the only fluid that supposedly will not harm paint if spilled on it. I sure didn't buy it for the low price....it is $35 a quart at the local NAPA store, about 2 1/2 times the cost of DOT 3.

 

[Ron H]

Something I've not been aware with dot 5 not harming paint.

 

[RJRENTON]

If Rick Ehrenberg uses it in classic cars, I'd trust it.
I have DOT 5 in my car. I did not mix it with anything. I wouldn't risk that.
Some claim it gives a mushy pedal. That hasn't been the case for me. I've finally got my brakes to a point where I have total confidence in them.
I decided to use it simply for the paint protection. DOT 5 is the only fluid that supposedly will not harm paint if spilled on it. I sure didn't buy it for the low price....it is $35 a quart at the local NAPA store, about 2 1/2 times the cost of DOT 3.

If Rick Ehrenberg used DOT 5 fluid on his Cheerios, SOME people WOULD do it...and think it's great.....DO NO MIX DOT 5 FLUID WITH ANY OTHER FLUID....IT'S TOTALLY DIFFERENT CHEMISTRY.....do your own research.....and common sense....
BOB RENTON

 

[1967coronet]

Use what the manual or cover lid calls for.
Do not mix brake fluid types.

 

[Cranky]

If Rick Ehrenberg uses it in classic cars, I'd trust it.
I have DOT 5 in my car. I did not mix it with anything. I wouldn't risk that.
Some claim it gives a mushy pedal. That hasn't been the case for me. I've finally got my brakes to a point where I have total confidence in them.
I decided to use it simply for the paint protection. DOT 5 is the only fluid that supposedly will not harm paint if spilled on it. I sure didn't buy it for the low price....it is $35 a quart at the local NAPA store, about 2 1/2 times the cost of DOT 3.

Have you 'tested' it on any paint yet?

 

[diesel_lv]

"Engineered" for DOT 3 in the 60's, they were all Engineered for DOT 3 then, because DOT 5 was not commercially available. The military has used purple DOT 5 for as long as i was in due to it freeze/boil points. No, do not mix DOT 3/4 w 5. But... as long as it's not ABS, you can flush and run DOT 5 in just about anything.

 

[Kern Dog]

Some of the most thick headed people I've met were engineers. Something about their schooling robs them of seeing the obvious.
I clearly stated that I didn't mix it and wouldn't risk it.
READ before you quote someone and call them out for their comments.

 

[Ron H]

Have you 'tested' it on any paint yet?

Nice idea; but if it's alright, please use it on your ride first, not mine..

 

[Kern Dog]

Have you 'tested' it on any paint yet?

I've had it in the car for almost a year now.
I had the engine and trans out in Summer 2022 and went through some changes with the brakes then. I tried a manual MC, then hydroboost (Failure!) then two different master cylinders on the A body booster, followed by ywo different MCs on this B body booster I now have. Each time involved some manner of brake bleeding and some spillage did happen. There has been no damage or even dulling of the paint.

 

[Cranky]

Some of the most thick headed people I've met were engineers. Something about their schooling robs them of seeing the obvious.
I clearly stated that I didn't mix it and wouldn't risk it.
READ before you quote someone and call them out for their comments.

I've had lots of experience with 'en-gin-neers' over the years.....and it was frustration to the max but now that I'm retired, I laugh about lots of it lol

 

[Photon440]

Because DOT 5 is silicone based, it is about as safe as synthetic car wax on your paint.

 

[Splangj]

Ok,ok! I said I believe he said mixing was ok, not certain about that. But I’m confident he said he uses dot 5 in his classic Mopars with no issues. I’m going to look it back up.

 

[Cranky]

Because DOT 5 is silicone based, it is about as safe as synthetic car wax on your paint.

I got a hold of some 100% silicone years ago and used it on a car with dead paint once....looked good for a few weeks then look like worse crap afterwards lol. Just an experiment.

 

[Ron H]

I've had lots of experience with 'en-gin-neers' over the years.....and it was frustration to the max but now that I'm retired, I laugh about lots of it lol

Had ample experience with engineers of one specialty or the next, having debated with them on one thing or another over the decades. The ones I usually had some, lets say ‘issues’ with, were those that never collected any dirt under their finger nails, often all college ‘smart’ never working in a shop for one friggin day. A few that peeved me most, not always, sorry just saying, were female. Longer story; but one occasion so royally pissed me off 25 years ago, can still recall it vividly today.

 

[Splangj]

Welp, I do feel RE is a hands on tech, and I can’t argue with any tech he’s printed. I’m sure there’s variables, but seems to be quite sane, and drives his **** hard.

 

[Splangj]

I’m unable to forward the whole article, for I am a lowly plumber. But he does claim to mix them….

 

[DeltaV]

DOT 5 and DOT 5.1 brake fluids are NOT the same.

DOT 5 is a silicone-base fluid.
DOT 5.1 is a glycol-ester fluid (some say polyglycol) and is compatible with DOT 3 and DOT 4 which are also glycol esters.