Advice on Swap to Dot 5 - New MC
Jos51
Bud Lindemann has tested every mopar muscle car and they are all on you tube, watch a few.
You said my statements were untrue and then said the same thing?
What do you think will happen if you add Dot 5 silicone to a Dot 3 system?
I think we're agreeing and not realizing it.
What happens when you add DOT 5 to a DOT 3 system? Nothing abnormal! Don't believe me? Ask Harley Davidson! They switched from DOT 5 to DOT 3 in the late 2000's. The
only part numbers in their system that changed were the master cylinder lids, because they indicated the change in spec fluid. All the seals and other parts were unchanged.
Plenty of mouthbreathing HD guys dumped in DOT5 without realizing that there had been a change. No problems! (Note, these are the same guys that think the fluid is being used, like engine oil, so they top it off, not realizing why they can't get the pistons to retract when it's time for new pads)
Correct. They do not mix.
and you might logically conclude it's not a good idea the put them in the same system if it can be helped.
Since the characteristics of both are different - in some ways opposite - having both in the same system would generally be counterproductive.
Rick E-berg has posted that military vehicles running SBBF have a sticker like this.
View attachment 1715362047
Certainly a fair number of manufactures advise not to mix.
eg.
https://www.penriteoil.com.au/assets/pdf/tech/Nov2015/Brake_Fluids.pdf
Rick E-berg has
always advised that it's ok to mix DOT 3 and DOT 5. The characteristics that are different have no effect on the functionality of the fluid.
Ask Penrite why they're wrong!
I sorta remember years and years ago,topping up a motorcycle reservoir with the correct fluid, according to the cap . I immediately saw I had done the wrong thing. I contacted the owner who said he had switched over to silicon. I had to remove what had become gunk.
It wasn't from mixing DOT 3/4 and 5. In 2004 I mixed all three in a baby food jar, and even punched a hole in the lid so it could absorb some moisture. I finally threw it away a couple years go. No gunk.
gunk..that would indicate some mixing unless the gunk was already in there AJ?
It seems that if they won't mix then the brakes should work fine as long as neither fluid will compress?
I don't think i'd add coolant to my engine oil but a different kind of lubricating oil or viscosity should be OK?
This person gets it.
My personal opinion about why they say not to mix is twofold.
#1, it's difficult to define what you can put in the system, and saying what can mix makes that more unclear. Mineral oil brake fluid, which is a thing, should
never be run in a 3/4/5/5.1 system. The materials in the cups and seals is totally different.
#2, Manufacturers have to dodge any liability arising from unclear instructions.