Synthetic Brake Fluid

[jamais]

I'm down to one sealed bottle of Prestone DOT 4 brake fluid so I went to the parts store to buy a couple of extra bottles. They've got Prestone DOT 4 packaged in the familar shaped bottle but with a different "look" and described as "synthetic". Its touted to be compatable with all DOT 4 systems including ABS.

This begs the question, is there any difference between the venerable DOT 4 fluid and the Synthetic product? Can I mix the two fluids and is our ABS system compatable with the synthetic?

I did a Google search of Prestone and there wasn't an answer. However I did find a reference to the new packaging look:

Danbury, CT - Honeywell Consumer Products selected Tom Fowler, Inc. to redesign their line of Prestone Brake Fluids. Taking the existing recognizable “brake fluid” bottle shape, Tom Fowler, Inc. changed the bottles’ color to the recognizable Prestone yellow and black to reinforce its brand presence on shelf. The label graphics continued with the Prestone yellow, and large bands of color in motion to quickly identify each product. The motion graphics infer “speed” for a quick working product. Offered in 32 and 12 oz bottles, they are now available in automotive, mass retailers and service stations nationwide.

Another store had the same "Synthetic" product in DOT 3, 4, and 5 grades. What's an anal retentive home mechanic to do?

[jamais]

I found this on the Valvoline brake fluid site, note the last item:

SynPower High Performance Synthetic Brake Fluid is recommended for ABS, hydraulic drum and disc braking systems and hydraulic clutches requiring DOT 3 and DOT 4 fluids. Its premium, synthetic, low-moisture formulation provides superior anti-vapor lock protection. It has a high dry-boiling point up to 500°F that reduces the risk of fluid vaporization and possible brake failure.

Exceeds DOT 3 and DOT 4 specifications
For most ABS, disc or drum brake systems
High boiling point reduces risk of brake failure
Compatible with conventional brake fluids

I still feel queasy. Why oh why do I hate change regarding maintenance? :eusa_wall:

[DarthRider]

There are pros & cons with DOT 5 brake fluid...I'm no expert so I'll just comment from personal experience.
There are some brake systems not compatible with DOT 5 fluid. It turned the seals & piston in my Norton's Lockheed master cylinder to a sticky, gooey liquid. Now that was a 1973 model and I tried the syn in 1982...current systems may all be compatible but I'd check first.

A great thing about DOT 5 is it won't eat paint like DOT 3 - 4...it just leaves a nice shine!

A guy I know, Mike Morse of Vintage Brakes in Cali swears by Castrol Dot 4 LWA (Low Water Absorption). He says it will buy you a time cushion if you're not religious about the annual fluid change and perform better throughout its' life.
He especially recommends it for we lucky soles who live in humid climates.
It's a little hard to find around here, I ordered some from a car racing supply website. It's no more expensive than others.

Dave

[Wild Will]

I've been using this stuff for years in my 1100 GS BMW. It's NOT silicone based, IS compatible with DOT 4, and from what the Motul guy told me at Laguna, it's not water absorbing, and has a higher boiling point (!). No rust or corrosion in my system, which I flush every year just like the book says.
DOT 4 is murder on paint, and supposedly (so far so good) DOT 5.1 is not, according to Mr. Motul.

[jamais]

I know your right Bill. Actually, I've done some more reading on the subject and DOT 4 compatable synthetic is actually referred to as 4.1 but we probably won't see that displayed anywhere on the containers.

As far as DOT 5 is concerned, I don't think I would go there.

[Wild Will]

Are you sure you don't mean 5.1? 4.1 is a new one to me!

[jamais]

Are you sure you don't mean 5.1? 4.1 is a new one to me!

You are right, I am wrong. Unfortunately my mistake left unchallenged is how misinformation gets out on the web for fact. I misread an article regarding Ducatis:

http://www.ducatimonster.org/faq/faq_brake_fluid.html