2nd Gen Non-Engine/Transmission Brake Fluid............

[CumminsPuller]

I am changeing the front pads on the truck today. And after 200,000 miles I was going to go ahead and change out the brake fluid in the system. My questions is: I think I have seen some DOT 5 brake fluid out there now? Is it better? Is it like motor oil where it is backward compatible?



Hurry, I am going out the door soon to go to the parts house... ... .



Thanks,



Jason

 

[CumminsPuller]

Went ahead and went to the parts house and found a bottle of the Silicon DOT 5. It says it is not compatible with ABS systems or systems that were previously filled with DOT 3 or 4.

 

[illflem]

Good move. DOT 5 isn't compatable with the rubber parts of systems designed for DOT 3&4.

You would have had a real mess on your hands.

 

[CumminsPuller]

illflem... ... ... . What effects does it have on the rubber parts? Just for future reference.



Jason

 

[illflem]

I have no experience with what DOT 5 does to rubber but have seen other chemicals that are incompatible turn rubber parts into melted goo. Using ATF in our power steering systems will do this to the hoses. I use rubber as a blanket term, there are hundreds of different types each with their own compatibilities.

 

[BudW]

DOT 5 shouldn’t have any effect (or is that affect?) on rubber or other brake items, if there are absolutely NO signs of DOT 3 or 4 left in the brake system.



Do not mix DOT 5 fluid with DOT 3 or 4 or bad things WILL happen.



I had a show car and I used DOT 5 brake fluid in it because it will not damage paint or most anything else on the car if you spill some. DOT 3 or 4 brake fluid will make the paint come right off.



If you have all new brake items (or flush out every single bit of the old stuff), then you are good to go, but for the cost difference and the labor hassle, you are better off using good ole DOT 3 or 4 brake fluid.



Bud

 

[fkovalski]

Which to use: 3 or 4 ?

Granted that DOT 3 & 4 are compatible, is one better than the other? What came stock in our trucks? I would like to stay with the same that came in the vehicle. I recall a TDR article a couple of issues back, but do not recall an actual recommendation.

 

[dresslered]

Dot 4 has a higher boiling specification and a slightly higher price. Unless you really heat up your brakes, either will work just fine. I'm sure that the truck came with DOT 3 but I would probably go to the DOT 4 since you can mix them.

 

[BudW]

DOT 4 is better than 3, and is a little more expensive, than DOT 3.



Your truck (and mine), is filled with DOT 3 from the factory.



Bud

 

[ronco]

The TDR magazine had a great and informative article on this very subject this year. If you are interested a better fluid than DOT 3 or 4, consider DOT 5. 1



It is still organic and can be mixed with the DOT 3 and 4. It is not compatible with the synthetic DOT 5, but to my knowledge, nothing else is compatible with synthetic.



The DOT 5. 1 has the same performance characteristics as the synthetic DOT 5 without the compatability issues.



Also, the synthetic fluid has larger "spaces" for entrained air that can leave a soft peddle in a large brake system. The 5. 1 does not have as much space for air.



Look thru your TDR magazines for all of the information listed above.



Ronco