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Ok to mix DOT3 with DOT4? #4686055
03/06/18 10:23 AM
03/06/18 10:23 AM
Joined: Feb 2016
Posts: 514
USA
DrRoughneck Offline OP
DrRoughneck  Offline OP
Joined: Feb 2016
Posts: 514
USA
My truck takes DOT3. I have a bottle of DOT4. Is it ok to top off the DOT3 with DOT4?

Re: Ok to mix DOT3 with DOT4? [Re: DrRoughneck] #4686062
03/06/18 10:30 AM
03/06/18 10:30 AM
Joined: Feb 2016
Posts: 663
NJ, USA
MotoTribologist Online confused
MotoTribologist  Online Confused
Joined: Feb 2016
Posts: 663
NJ, USA
Originally Posted By: DrRoughneck
My truck takes DOT3. I have a bottle of DOT4. Is it ok to top off the DOT3 with DOT4?

Yes, both DOT 3 and DOT 4 are miscible with one another and are typically compatible glycol based fluids.

Re: Ok to mix DOT3 with DOT4? [Re: DrRoughneck] #4686102
03/06/18 11:23 AM
03/06/18 11:23 AM
Joined: Jan 2009
Posts: 6,167
New England
gathermewool Offline
gathermewool  Offline
Joined: Jan 2009
Posts: 6,167
New England
And 5.1 (not to be confused with 5.0)

3, 4, 5.1 - all compatible.


'14 Forester XT (Cobb Stage 1)
Edge 0W-40 + FU filter
'15 Legacy 2.5i (OEM Stage -7)
Edge 0W-20 + FU filter
Re: Ok to mix DOT3 with DOT4? [Re: DrRoughneck] #4686207
03/06/18 12:54 PM
03/06/18 12:54 PM
Joined: Apr 2017
Posts: 923
SF BAY AREA, CA
dogememe Offline
dogememe  Offline
Joined: Apr 2017
Posts: 923
SF BAY AREA, CA
yes, you can mix. If you have multiple vehicles and prefer to just stock one, just keep dot4 on hand, it works on both.


2007 Crown Vic P71 4.6 ~126K Miles, Royal Purple HPS 5W-30, Royal Purple Filter, Daily Driver.
2010 Escape FWD 2.5 ~84K Miles, Castrol Edge EP 5W-30, Wix Filter, Rented on Turo.
Re: Ok to mix DOT3 with DOT4? [Re: DrRoughneck] #4686215
03/06/18 01:00 PM
03/06/18 01:00 PM
Joined: Feb 2015
Posts: 2,193
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,193
Slovenia EU
And dont forget to cure the cause for topping off!

You can have leak somewhere...or! Level between MAX-MIN usually coresponds with how much worn out your brakes are wink

Last edited by Kamele0N; 03/06/18 01:03 PM.

2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: Ok to mix DOT3 with DOT4? [Re: gathermewool] #4686676
03/06/18 08:09 PM
03/06/18 08:09 PM
Joined: Mar 2008
Posts: 6,791
USA
slacktide_bitog Online content
slacktide_bitog  Online Content
Joined: Mar 2008
Posts: 6,791
USA
Originally Posted By: gathermewool
And 5.1 (not to be confused with 5.0)

3, 4, 5.1 - all compatible.


approved

Re: Ok to mix DOT3 with DOT4? [Re: DrRoughneck] #4688778
03/08/18 03:15 PM
03/08/18 03:15 PM
Joined: May 2014
Posts: 3,656
Columbus,Nebraska
Yah-Tah-Hey Online content
Yah-Tah-Hey  Online Content
Joined: May 2014
Posts: 3,656
Columbus,Nebraska
Valvoline brake fluid is DOT3/DOT4 so what do you think?

Re: Ok to mix DOT3 with DOT4? [Re: Kamele0N] #4688821
03/08/18 04:02 PM
03/08/18 04:02 PM
Joined: Jan 2004
Posts: 4,142
California
nthach Offline
nthach  Offline
Joined: Jan 2004
Posts: 4,142
California
Originally Posted By: Kamele0N
And dont forget to cure the cause for topping off!

You can have leak somewhere...or! Level between MAX-MIN usually coresponds with how much worn out your brakes are wink

Yep - I never top off brakes as the level sinks and rises according to how worn the friction is. There is never a need to top off a brake system. If you're constantly losing brake fluid you have a leak somewhere - but you can feel it in the pedal in most cases.


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