Dot 5 brake fluid

[john302]

Has anyone heard that dot 5 brakefluid is different now ? Have used it for years in 67-69 Camaros with zero problems . But have not used any in awhile . Heard the formula is changed now and people are having problems with it ? thanks

[rich69rs]

I've also used DOT 5 brake fluid for probably 20+ years in my '66 Chevelle & '69 Camaro RS and am still using it.

Haven't had any issues to date.

Richard

[x66 714]

I had major problems. It was eating all the rubber brake pieces. I 1st discovered weeping from the jackets of the new brake hoses. I bled the system & discovered the fluid was grey & had tiny black specs. I ended up draining the entire system & flushing with denatured alcohol. One that was done, I had to take every brake component apart to put new kits in. Once I did that, I ran 2 quarts of dot 4 through the system. Now everything is fine. I forgot to mention that the master cyl, calipers, wheel cyls, & all the hose were brand new & everything was offshore. Mike Gibbons also will not warrantee any of his rebuilds if dot 5 is used....Joe

[x66 714]

I copied this from White Post Restoration....Joe

Lifetime Warranty
We fully guarantee all parts that are sleeved and/or rebuilt by us, with the exception of those used in conjunction with silicone fluid (DOT 5).

[169INDY]

I use DOT 5 in Three Cars with No problems;

Often the Problems are related to age and lack of use and proper maintenance.

Personally, as a show driver car the risk to paint finish is way more a hazard than the detrimental effects possible to soft goods but I do acknowledge that many rebuilders with Huge amounts of experience are ANTI DOT 5.

DOT3 make a Great Paint stripper!!!!!!!!!!!!!!!!

[GMAD_Van Nuys]

The 2025 Corvette uses DOT 4 brake fluid:

https://www.chevrolet.com/content/dam/chevrolet/na/us/english/index/vehicles/2020/performance/corvette-experience/02-pdf/02-pdf/2025_Corvette_Track_Guide_Final.pdf

While DOT 5.1 brake fluid was developed so it could be used in vehicles with ABS, it would take a lot of effort to remove all the DOT 3 or 4 fluid from the system to avoid contamination.  If you had problems that resulted in using DOT 5.1, I doubt that the manufacturer would reimburse you to repair your brake system. 

[camaronut]

I've been using DOT 5 for years.....never an issue......Plus my master cylinder was rebuilt by White Post.

[boomer632]

Lonestar Caliper will void warranty if Dot5 is used in one of their rebuilds
Im just going to go Dot 3 just to be safe when I install my calipers and MC

[GMAD_Van Nuys]

I just flushed the brake fluid on 2 vintage cars and also used DOT 3.

[70z28lt1]

Just went through this with my car.
new parts, never any exposure to DOT 3 or other.  New lines, rebuilt Master by Apple Hydraulics.  Rebuilt booster and rear proportional valve and distribution block by Steve Gregori at BrakeBoosters.com (pre Mike Gibbons).
All new lines,seal etc.

Pressure bled system with DOT 5.  Great, firm pedal.

Car sat (not driven) for ~2 months and noticed a puddle under the frame where the booster-MC is.  Bottom of master was wet and a drip was hanging from the rear proportional valve.
Pulled the master and PP valve.  Disassembled and all the seals looked good.  No swelling or deterioration seen.  Looked at the bore of the brass sleeved MC and it had some what I consider rough cross hatches from the hone operation.  I was not happy with this and took some 2000 grit paper and polishing compound and worked until a mirror finish on the seal surface.
Opened up the rear PP valve and saw a scratch along the seal diameter about 0.003 to 0.005 deep.  Definately a leak path.  I took a sanding tootsie roll and carefully worked this out, blending about half way around the diameter.  Then polished the entire diameter.  Re-assembled and pressure bled.  3 months later not a drop from anywhere.  Pedal is good.
The bottom line is, in my estimation maybe DOT 5 is more prone to imperfections and sealing surfaces have to be very good.  I was disappointed at the workmanship on the rebuilds, but maybe they would have been OK with DOT 3.  Don't know.
I know the rebuilders don't like DOT 5 and maybe its due to the above.  I do know that if you spill DOT 3 or if the rebuilt part leaks and damages an expensive paint job, will they reimburse you for the paint work?  I think we all know the answer to that.  It's just not worth the risk to me.  If I had used DOT 3 and it leaked as the 5 did, I would be out thousands in paint repair to disamantle and pull the subframe to fix it.  If you have a driver level car and you are not worried about having good paint, go for it and use DOT 3 (or 4 or 5.1).
I now categorize any rebuilt-restored part as an engine rebuild.  Get good folks doing the work, but trust that no one did the job right.  When assembling your engine, verify that all the machining was done correct and that all clearances are correct.
When I was contemplating using DOT 5 I read about every post I could find on the subject and it ran about 50-50 on folks that swear by it and folks that swear at it.  Nothing absolutely definitive one way or the other.
FWIW here is the fluid I used:
https://www.amazon.com/dp/B002IAS82W?th=1
I'm not going to say it's the best out there, but it works for me.  There are higher priced ones, but when you compare the MSDS's they all seem to be the same as the Johnsens.
Good luck.

[rich69rs]

The bottom line is, in my estimation maybe DOT 5 is more prone to imperfections and sealing surfaces have to be very good.  I was disappointed at the workmanship on the rebuilds......I know the rebuilders don't like DOT 5 and maybe it's due to the above. 

I do know that if you spill DOT 3 or if the rebuilt part leaks and damages an expensive paint job, will they reimburse you for the paint work?  I think we all know the answer to that.  It's just not worth the risk to me.  If I had used DOT 3 and it leaked as the 5 did, I would be out thousands in paint repair to disamantle and pull the subframe to fix it.  If you have a driver level car and you are not worried about having good paint, go for it and use DOT 3 (or 4 or 5.1)

Get good folks doing the work, but trust that no one did the job right.  When assembling your engine, verify that all the machining was done correct and that all clearances are correct.

Exactly

Reminds me of a thread a few years ago on this forum where someone was stating that Pertronix had a 50% failure rate on their electronic distributor conversion kits - which was obviously not an accurate fact.  But since he couldn't make it work - fault had to be with Pertronix.

Always easier to assign blame than address root cause.

Richard

[Mike S]

 Been running DOT 5 in the restored Camaro since 2018 with no problems and never had to top off the M/C.

Mike