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Does motor oil and DOT 3 brake fluid mix? #4713343
04/01/18 02:31 PM
04/01/18 02:31 PM
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
JAG Offline OP
JAG  Offline OP
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
Why would I ask such a thing? Science, only. No practical reason. I have the answer and want to see what your guesses are and why you think your answer is correct.

Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713358
04/01/18 02:40 PM
04/01/18 02:40 PM
Joined: Mar 2013
Posts: 5,126
The Midwest
skyactiv Offline
skyactiv  Offline
Joined: Mar 2013
Posts: 5,126
The Midwest
DOT 3 brake fluid and engine oil doesn't mix, but DOT 4 does since you didn't include it.


Wife: 15' Audi A4 quattro 6 speed manual
Me: 13' VW GTI 3 door 6 speed manual
Wanted: 2019 Ford Ranger
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713367
04/01/18 02:50 PM
04/01/18 02:50 PM
Joined: Dec 2016
Posts: 7,443
Waco, TX
Linctex Offline
Linctex  Offline
Joined: Dec 2016
Posts: 7,443
Waco, TX
Dot 3 is glycerin based, so is miscible with water and alcohol

It'll sink to the bottom of the oil pan.


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713373
04/01/18 03:01 PM
04/01/18 03:01 PM
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
JAG Offline OP
JAG  Offline OP
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
You guys are correct about DOT 3 not mixing with motor oil. With agitation, I got it to somewhat mix, but after sitting still for a while, the two fluids separated.

Linctex somewhat touched on the why no miscibility. Why do they not mix?

Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713407
04/01/18 03:43 PM
04/01/18 03:43 PM
Joined: Mar 2018
Posts: 142
Hammehead Offline
Hammehead  Offline
Joined: Mar 2018
Posts: 142
GOOD STUFF HERE

Last edited by Hammehead; 04/01/18 04:08 PM.

ToYota Corolla XEI 2010 1zzfe
Kawasaki Ninja ZX9R B4
Taurus GL Vulcan
Citroen C5 phase I
I used to use syn, now whatever is on sale and never had problems. This noob knows stuff.
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713491
04/01/18 05:52 PM
04/01/18 05:52 PM
Joined: Dec 2002
Posts: 41,933
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 41,933
'Stralia
Polarity and MW ?

On topic, we use a lot or re-refined oil for auxiliary fueling the boilers at work (250,000L for a cold start), 10-14Cst blend of used re-refined oil and diesel.

We had huge blockage issues a couple years ago. 5um filter as it goes onto the truck, and 25um filters blocked at the boiler.

Turned out to be glycol in the waste streams surviving the re-refiner, and then collecting (agglomerating soot particles, and forming quite strong stable particles).

They upper the upper temperature of the re-refiner, and problem went away.

Re: Does motor oil and DOT 3 brake fluid mix? [Re: Shannow] #4713499
04/01/18 06:04 PM
04/01/18 06:04 PM
Joined: Oct 2012
Posts: 4,825
Taiwan
Ducked Offline
Ducked  Offline
Joined: Oct 2012
Posts: 4,825
Taiwan
Originally Posted By: Shannow
Polarity and MW ?


Turned out to be glycol in the waste streams surviving the re-refiner, and then collecting (agglomerating soot particles, and forming quite strong stable particles).



Is that necessarily from brake fluid (glycol ether) or could it be from coolant (ethylene or propylene glycol)?

Probably more coolant being disposed of than brake fluid, and its known to cause that kind of thing in an operating engine with, say, a popped head gasket.

I keep my used brake fluid for cleaning things. You can't buy water-miscible brush cleaner any more.

Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713501
04/01/18 06:05 PM
04/01/18 06:05 PM
Joined: Sep 2004
Posts: 7,902
Marshfield , MA
andyd Offline
andyd  Offline
Joined: Sep 2004
Posts: 7,902
Marshfield , MA
I have a few jars of used BF. I keep it around for air locks when I bleed. I don't like it on my skin and it tastes terrible. Is there any practical use for it? If not whats the best way to get rid of it?


'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2
Re: Does motor oil and DOT 3 brake fluid mix? [Re: Shannow] #4713506
04/01/18 06:11 PM
04/01/18 06:11 PM
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
JAG Offline OP
JAG  Offline OP
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
Originally Posted By: Shannow
Polarity and MW ?

On topic, we use a lot or re-refined oil for auxiliary fueling the boilers at work (250,000L for a cold start), 10-14Cst blend of used re-refined oil and diesel.

We had huge blockage issues a couple years ago. 5um filter as it goes onto the truck, and 25um filters blocked at the boiler.

Turned out to be glycol in the waste streams surviving the re-refiner, and then collecting (agglomerating soot particles, and forming quite strong stable particles).

They upper the upper temperature of the re-refiner, and problem went away.

Yes, the polarities of DOT 3 and motor oil are too dissimilar to allow miscibility. The brake fluid is more polar. Perhaps at high enough temperature they would be miscible but not at room temp. and 125F.

I ended up adding the brake fluid because for weeks I had been experimenting with seeing if motor oil would dissolve a sliver of varnish that was composed solely of oxidized vegetable oil. The answer was ďsort of, but mostly noĒ. I used Amsoil 10W-30, Maxima Formula K2 2-stroke oil (mostly esters), and Hy-per Lube polymer esters, separately. They did soften the varnish and give it flexibility that it lacked when dry. It also swelled. With gentle shaking, they did cause it to partially split apart. A very small piece or two did break off. Today I added brake fluid to the Amsoil that was already there. The varnish got even more flexible and swollen. Quite a few chunks broke off. The varnish became the consistency of mucous. DOT 3 is definitely more capable of dissolving vegetable oil varnish than the three other fluids I tested.

Thatís an interesting story about the blockage from ethylene glycol.

Re: Does motor oil and DOT 3 brake fluid mix? [Re: andyd] #4713515
04/01/18 06:19 PM
04/01/18 06:19 PM
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
JAG Offline OP
JAG  Offline OP
Joined: Oct 2005
Posts: 5,128
Fredericksburg, VA
Originally Posted By: andyd
I have a few jars of used BF. I keep it around for air locks when I bleed. I don't like it on my skin and it tastes terrible. Is there any practical use for it? If not whats the best way to get rid of it?

You tasted it!? :-) I donít know if itís frowned upon but I plan on delivering used oil to a disposal place with a little bit of brake fluid in it. You could ask your collection place whether they accept brake fluid.

Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713519
04/01/18 06:24 PM
04/01/18 06:24 PM
Joined: May 2013
Posts: 688
Florida
SilverSnake Offline
SilverSnake  Offline
Joined: May 2013
Posts: 688
Florida
Originally Posted By: JAG
Why would I ask such a thing? Science, only. No practical reason. I have the answer and want to see what your guesses are and why you think your answer is correct.


You should never have brought this up. Someone on this forum will try putting it in their oil to "put the brakes" on oil deterioration to squeeze a few more miles out of an oil change.


2016 Charger, 6.4L-485 HP (PUP 0W-40)
2017 BMW 330i, 2L-248 HP (BMW 0W-20)
2018 Jeep GC, 5.7L-360 HP (PUP 5W-20)
2008 20KW Generac (Amsoil 10W-30/30)
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713534
04/01/18 06:38 PM
04/01/18 06:38 PM
Joined: Dec 2002
Posts: 41,933
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 41,933
'Stralia
When I went to sell the plastic rocker covers from my L67, they were heavily varnished.

Solvents just didn't touch it...a caustic based shop degreaser just ate through it/

When we had to clean the turbine oil tanks, caustic based clearners and hot water were the only way to get the crud out.

Save the glycol for wood preserver...sure that it would work like Ethylene Glycol...

https://www.bobistheoilguy.com/forums/ub...ool#Post4695285

Re: Does motor oil and DOT 3 brake fluid mix? [Re: andyd] #4713540
04/01/18 06:42 PM
04/01/18 06:42 PM
Joined: Oct 2012
Posts: 4,825
Taiwan
Ducked Offline
Ducked  Offline
Joined: Oct 2012
Posts: 4,825
Taiwan
Originally Posted By: andyd
I have a few jars of used BF. I keep it around for air locks when I bleed. I don't like it on my skin and it tastes terrible. Is there any practical use for it? If not whats the best way to get rid of it?


See my post immediately above. (I'm afraid I used ritten wurdz. I'm too lazy to make youtube videos just to communicate effectively with Americans)

Specifically, it makes a good carburettor cleaner, and MIGHT therefore be effective on intake deposits on trendy DI engines.

I've heard of it being used as a decoker/ring unsticker, but I might want to use fresh stuff for that unless the used stuff was really clean.

Its water miscibility means it can be effectively combined with water washing, as in boil-washing carburettors.

Last edited by Ducked; 04/01/18 06:43 PM.
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713547
04/01/18 06:53 PM
04/01/18 06:53 PM
Joined: Jul 2003
Posts: 4,960
New Zealand
Silk Offline
Silk  Offline
Joined: Jul 2003
Posts: 4,960
New Zealand
Engine oil doesn't work well in a brake system, I don't think the reverse is any good either.


1987 BMW R65 - Aegis SAE30
2005 Nissan Expert - Gulf Western 10W-40
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.
Re: Does motor oil and DOT 3 brake fluid mix? [Re: JAG] #4713591
04/01/18 07:41 PM
04/01/18 07:41 PM
Joined: Mar 2008
Posts: 7,517
USA
slacktide_bitog Offline
slacktide_bitog  Offline
Joined: Mar 2008
Posts: 7,517
USA
Don's some people add brake fluid to the engine if it's leaking bad? hide crush oilburner

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