3 DOT vs. 5 DOT Fluid Which is best for trucks?
#1
12-03-2007, 12:31 AM
3 DOT vs. 5 DOT Fluid Which is best for trucks?
I was wondering if anyone has had some experience with the differences with 3 DOT and 5 DOT brake fluid. I like the idea of DOT 5 is silicone fluid and easier is on paint and rubber parts but don't want a problem with the performance. I have a 60 4x4 3/4 ton and do drive down some steep grades on hot days. Appreciate any help. Thanks.
#2
12-03-2007, 12:52 AM
Logistics Pro
DOT 3 or DOT 4 is probably the best to use. DOT 3/4 is water soluble and DOT 5 is not.
Here's a great discussion on each.
http://www.xs11.com/tips/maintenance/maint1.shtml
And more! http://www.se-r.net/brakes/fluid.html
Cheers,
Rick
Here's a great discussion on each.
http://www.xs11.com/tips/maintenance/maint1.shtml
And more! http://www.se-r.net/brakes/fluid.html
Cheers,
Rick
#3
12-03-2007, 04:51 AM
#4
12-03-2007, 12:01 PM
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Dot 5
Dot 5 has a higher heat tolerance. Dot 5 doesn't have brake line/caliber moisture that causes corrosion. It is a silicone material. I am using it in my Harley and three previous corvettes. The pedal is firmer due to differences in fluid. As easy to bleed. Works great for me. Have a great day,chuck
#5
12-03-2007, 12:50 PM
Logistics Pro
Uh....DOT 5 doesn't prevent moisture incursion. It just doesn't dissolve the moisture and keep in solution. With Dot 5 you end up with bubbles of water in the lowest part of the brake system. Not a good thing.
From: http://www.xs11.com/tips/maintenance/maint1.shtml
Here's what another said about DOT5
I tried it once in a motorcycle.
I would NEVER go back to DOT 5 and it appears that most automotive manufacturers didn't either.
Do a google search on DOT 3/4/5 and you'll find all the info you need.
I suggest using DOT 3 or 4 and change it once in a while.
Regards,
Rick
From: http://www.xs11.com/tips/maintenance/maint1.shtml
Water absorption and corrosion
The big bugaboo with DOT 3-4 fluids always cited by silicone fluid advocates is water absorption. DOT 3-4 glycol based fluids, just like ethylene glycol antifreezes, are readily miscible with water. Long term brake system water content tends to reach a maximum of about 3%, which is readily handled by the corrosion inhibitors in the brake fluid formulation. Since the inhibitors are gradually depleted as they do their job, glycol brake fluid, just like anti-freeze, needs to be changed periodically. Follow BMW's recommendations. DOT 5 fluids, not being water miscible, must rely on the silicone (with some corrosion inhibitors) as a barrier film to control corrosion. Water is not absorbed by silicone as in the case of DOT 3-4 fluids, and will remain as a separate globule sinking to the lowest point in the brake system, since it is more dense.
The big bugaboo with DOT 3-4 fluids always cited by silicone fluid advocates is water absorption. DOT 3-4 glycol based fluids, just like ethylene glycol antifreezes, are readily miscible with water. Long term brake system water content tends to reach a maximum of about 3%, which is readily handled by the corrosion inhibitors in the brake fluid formulation. Since the inhibitors are gradually depleted as they do their job, glycol brake fluid, just like anti-freeze, needs to be changed periodically. Follow BMW's recommendations. DOT 5 fluids, not being water miscible, must rely on the silicone (with some corrosion inhibitors) as a barrier film to control corrosion. Water is not absorbed by silicone as in the case of DOT 3-4 fluids, and will remain as a separate globule sinking to the lowest point in the brake system, since it is more dense.
DOT5
DOT5 brake fluid is also known as "silicone" brake fluid.
Advantages:
DOT5 doesn't eat paint.
DOT5 does not absorb water and may be useful where water absorption is a problem.
DOT5 is compatible with all rubber formulations. (See more on this under disadvantages, below.)
Disadvantages:
DOT5 does NOT mix with DOT3, DOT4 or DOT5.1. Most reported problems with DOT5 are probably due to some
degree of mixing with other fluid types. The best way to convert to DOT5 is to totally rebuild the hydraulic
system.
Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5
formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent
formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will "puddle" in one place. This can
cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form
large bubbles over time. It may be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a lower boiling point than DOT4.
DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find, generally only available at selected
auto parts stores.
DOT5 brake fluid is also known as "silicone" brake fluid.
Advantages:
DOT5 doesn't eat paint.
DOT5 does not absorb water and may be useful where water absorption is a problem.
DOT5 is compatible with all rubber formulations. (See more on this under disadvantages, below.)
Disadvantages:
DOT5 does NOT mix with DOT3, DOT4 or DOT5.1. Most reported problems with DOT5 are probably due to some
degree of mixing with other fluid types. The best way to convert to DOT5 is to totally rebuild the hydraulic
system.
Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5
formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent
formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will "puddle" in one place. This can
cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form
large bubbles over time. It may be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a lower boiling point than DOT4.
DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find, generally only available at selected
auto parts stores.
I tried it once in a motorcycle.
I would NEVER go back to DOT 5 and it appears that most automotive manufacturers didn't either.
Do a google search on DOT 3/4/5 and you'll find all the info you need.
I suggest using DOT 3 or 4 and change it once in a while.
Regards,
Rick
Originally Posted by 49fordpickumup
Dot 5 has a higher heat tolerance. Dot 5 doesn't have brake line/caliber moisture that causes corrosion. It is a silicone material. I am using it in my Harley and three previous corvettes. The pedal is firmer due to differences in fluid. As easy to bleed. Works great for me. Have a great day,chuck
Last edited by HT32BSX115; 12-03-2007 at 12:52 PM.