Ok cize ROZSUDOK ZNIE : technicky je to jedno (cize sa nic nepokazi) ale koli zaruke sa oplati dat originalny olej vyrobcu ... !!! dakujem vsetkym ktory sa snazili svojimi radami prispiet k tomuto sudu 
Prrrrr, aky lock? Nahodou celkom zaujimava tema. O tom DOT 5 na baze silikonu som napr. nevedel a celkom ma zaujal. Tak som minul 2 minuty navyse a vygooglil som celkom zaujimave info, z ktoreho mi vychadza, ze DOT 5 do mojich brzd radsej vzhladom na mozne problemy s tesneniami a odvzdusnovanim nepouzijem...
"Should I use DOT 3, 4 or 5 brake fluid when replacing?"
DOT 3 and DOT 4 are functionally very similar. 4 has a higher boiling point, but motorcycle brake systems don't generate the kind of pressure and temperatures that need it on the street, in general, although it certainly won't hurt your system to put it in.
DOT 5 is very different - it's silicone based, doesn't absorb water, isn't corrosive, is bad for some seals, is hard to bleed, and is not miscible with 3 or 4. Stay away from it - it needs a system designed for it. And it comes as stock item in Harley's, so it must be terrible.
DOT 5.1 is compatible with DOT 3 & DOT 4 (If I ever get hold of the bonehead who named DOT 5.1...)
Here's more detail than you really want:
DOT3 is an aliphatic polyether.
DOT4 is borate ester based.
DOT5 is polydimethylsiloxane (silicone based).
DOT5.1 is borate ester based, thus its compatibility with DOT3 and DOT4.
More information can be obtained from the following standards documents:
DOT3: SAE J1703
DOT4: FMVSS 116; proposed SAE standard J1704
DOT5: SAE J1705
DOT5.1: No SAE spec
If you are interested in obtaining copies of these standards documents, you may order them directly from SAE at http://www.sae.org/PRODSERV/STANDARD/gv/179.htm.
According to DOT Federal Motor Vehicle Safety Standards specification 49CFR571.116 (which refers to SAE documents J1703, J1704, J1705), the minimum equilibrium reflux boiling point requirement in deg C for each is:
DOT 3 205
DOT 4 230
DOT 5 260
DOT 5.1 260
This shows that, all else remaining the same, DOT 5.1 has a significant advantage in heat capacity over DOT 4. Note that these specifications are for completely dry (no H2O content) brake fluid.
Of course, all else does not remain the same and other than boiling points and H2O content (which is very detailed in itself), most other properties were beyond the scope of testing/interest of my friend. Any other information should be gained from SAE, DOT or other authority.
"Should I use DOT 3, 4 or 5 brake fluid when replacing?"
DOT 3 and DOT 4 are functionally very similar. 4 has a higher boiling point, but motorcycle brake systems don't generate the kind of pressure and temperatures that need it on the street, in general, although it certainly won't hurt your system to put it in.
DOT 5 is very different - it's silicone based, doesn't absorb water, isn't corrosive, is bad for some seals, is hard to bleed, and is not miscible with 3 or 4. Stay away from it - it needs a system designed for it. And it comes as stock item in Harley's, so it must be terrible.
DOT 5.1 is compatible with DOT 3 & DOT 4 (If I ever get hold of the bonehead who named DOT 5.1...)
Here's more detail than you really want:
DOT3 is an aliphatic polyether.
DOT4 is borate ester based.
DOT5 is polydimethylsiloxane (silicone based).
DOT5.1 is borate ester based, thus its compatibility with DOT3 and DOT4.
More information can be obtained from the following standards documents:
DOT3: SAE J1703
DOT4: FMVSS 116; proposed SAE standard J1704
DOT5: SAE J1705
DOT5.1: No SAE spec
If you are interested in obtaining copies of these standards documents, you may order them directly from SAE at http://www.sae.org/PRODSERV/STANDARD/gv/179.htm.
According to DOT Federal Motor Vehicle Safety Standards specification 49CFR571.116 (which refers to SAE documents J1703, J1704, J1705), the minimum equilibrium reflux boiling point requirement in deg C for each is:
DOT 3 205
DOT 4 230
DOT 5 260
DOT 5.1 260
This shows that, all else remaining the same, DOT 5.1 has a significant advantage in heat capacity over DOT 4. Note that these specifications are for completely dry (no H2O content) brake fluid.
Of course, all else does not remain the same and other than boiling points and H2O content (which is very detailed in itself), most other properties were beyond the scope of testing/interest of my friend. Any other information should be gained from SAE, DOT or other authority.
Alebo kamosa, ktory Ti to prelozi ked si lenivy. 
mam par dalsich otazok:
je rozdiel v stlacitelnosti medzi DOT4 a DOT5.1
je rozdiel v absorpcii vody medzi min. olejom a brzd. kvapalinou
je potrebne vymienat aj min. olej kazdy rok
je rozdiel v stlacitelnosti medzi DOT4 a DOT5.1
je rozdiel v absorpcii vody medzi min. olejom a brzd. kvapalinou
je potrebne vymienat aj min. olej kazdy rok
mam par dalsich otazok:
je rozdiel v absorpcii vody medzi min. olejom a brzd. kvapalinou
je potrebne vymienat aj min. olej kazdy rok
je rozdiel v absorpcii vody medzi min. olejom a brzd. kvapalinou
je potrebne vymienat aj min. olej kazdy rok
Olej asi neabsorbuje vodu vobec - mam ho v brzdach uz treti rok bez zasahu.
Tiez je vyhoda, ze je menej agresivny, takze pri vymene mozes byt menej opatrny
Ak by som mal vybrat z podobnych brzd a prevedenie DOT vs. olej, uprednostnil by som olej.
