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Garage => Mechanicals => Topic started by: rumb on 24 March 2020, 09:29 AM

Title: DOT 4+
Post by: rumb on 24 March 2020, 09:29 AM
I learned something new today.  MB sells DOT4+ brake fluid.  I had not heard of it before.

- DOT 5.1 brake fluids

Historically, DOT 5-level performance (specifically boiling points and viscosity) could only be achieved with silicone-based fluids. However, modern compositions have created glycol ether-based fluids which now meet DOT 5 brake fluids requirements in these key areas. Consequently, the DOT 5.1 brake fluids level was created to differentiate these two very different chemistries which both meet DOT 5 brake fluids performance requirements.
In so many words, DOT 5.1 brake fluids are simply DOT 4-type brake fluids which meet DOT 5 brake fluids performance requirements. Because of this, they typically can be mixed with DOT 3 or DOT 4 brake fluids without concern. Sometimes, they are even referred to as 'DOT 4 Plus' or 'Super DOT 4' brake fluids because they are more similar to a conventional DOT 4 fluid by chemistry than they are to a conventional DOT 5 brake fluid. In fact, DOT 5.1 is essentially comprised of borate esters.
Title: Re: DOT 4+
Post by: ptashek on 24 March 2020, 01:03 PM
It's sometimes also sold as "full-synthetic DOT4"
Title: Re: DOT 4+
Post by: Diesel 617 on 25 March 2020, 09:42 PM
Also to add to this I called up ATE about their Dot 4 and Dot 4 SL fluids and they can be safely mixed.
Title: Re: DOT 4+
Post by: Randys01 on 26 March 2020, 03:15 AM
Gee.  how did we survive DOT 1?  I've been associated with a "fair bit" of competition in 60 years and man!.....only twice have I boiled the brake fluid and you should have witnessed the abuse it took.  :P
I have hammered my 6.9 uphill and down dale and just got them to fade.  I cannot fade the brakes on my GTR let alone boil the fluid. ...and the fluid is  is old and Yes....I do need to replace it  ...but Hello?.  They are marketing bulltwang spec to Ma and Pa Kettle who barely get over 40 mph and have one heavy stop in a lifetime.
Scheduled replacement of these fluids every 2 years..scheduled replacement of glycol coolant every  2 years...the list of "jobs for the boys" seems endless.
My daughter in law was quoted a power stg flush on a car that had electric steering.?!! You need to the pollen filter changed every 20 minutes............
Cripes...give us a break.

Title: Re: DOT 4+
Post by: ptashek on 26 March 2020, 11:02 AM
Quote from: Randys01 on 26 March 2020, 03:15 AM
Gee.  how did we survive DOT 1?  I've been associated with a "fair bit" of competition in 60 years and man!.....only twice have I boiled the brake fluid and you should have witnessed the abuse it took.

Ditto.
I've managed to stress brake fluid to a point where the brakes started fading really bad only once in nearly 30 years of driving. Of all things, it was a rental Chevy Cruze on a very long 9% downhill gradient on the CA-190 going East out of Death Valley. Not what I'd describe as "fun" :D