Quick question about brake fluids

tommigun · Post by **tommigun** » Fri Aug 03, 2007 1:47 am

Hello.

A quick question: Can I mix DOT3 and DOT4+ fluids together? I've tried to google and I've tried to search but I haven't found a simple answer. I'm doing some maintenance work with the brakes and might need to add some fluid so I was just thinking if I could use the fluid we have at work.

Thanks.

j0n · Post by **j0n** » Fri Aug 03, 2007 1:59 am

as long as your brake system uses at least dot 3 you'll be fine...if you read the bottle on dot4+ it says that it "meeets or exceeds the standards of dot 3"

tommigun · Post by **tommigun** » Fri Aug 03, 2007 7:36 am

Yeah. I was just wondering if there will be any sort of chemical reaction or something if DOT3 and DOT4+ have too different ingridients. But it is safe to top the reservoir with DOT4+ with excisting DOT3 in the system?

Post by **Diablo0** » Fri Aug 03, 2007 8:53 am

Just make sure the DOT4 says it's compatable with DOT3 fluid... usually it'll say it on the bottle.

ewetho · Post by **ewetho** » Fri Aug 03, 2007 10:52 pm

You can use
DOT 3
DOT 4 or
DOT 5.1

DO NOT USE
DOT 5 or other silicone fluids. NOT Compatible.

As far as mixing several DOT 4 fluids are their DOT 3 fluid as well. Sort of like same basic fluid with higher specs.

OB · Post by OB » Fri Aug 03, 2007 11:46 pm

I've always heard NOT to mix any two fluids. The brake system works with DOT 4, but mixing them isnt a great idea. If necessary as a temporary fix, no worries, but I would suggest sticking with one or the other.

tommigun · Post by **tommigun** » Tue Aug 07, 2007 5:14 pm

Thanks for the info guys. I didn't lose too much fluid so I just topped it of with DOT4+ and so far no problems. Once I save enogh money I'll still probably take the car to dealership for a fluid change.

ewetho · Post by **ewetho** » Fri Aug 10, 2007 11:32 pm

Most of the fluids are very close. Would not worry about brands so much. Heck Valvoline and Castrol make a fluid that is both 3 and 4 now what??? Use Dot 4 stuff in Dot 4 Cars. Heck use it in DOT 3 cars too. Just not 3 in a 4 car.