I have used DOT5 on all my classic cars for over 40 years primarily because of it's non-aggressive nature towards paint-- bleeding always seems to get fluid on something. However, it is not without it's risks.
It is non-hydroscopic which means it does not absorb water, but that characteristic can be both good and bad. With heat cycling, condensation will almost always show up in brake hydraulics-- DOT 3/4 will hold this water more or less harmlessly in suspension while DOT5 rejects this condensation and allows it to pool in the low spots in the system. Unfortunately, bleed screws are designed to eliminate air which naturally goes to the high points making it sometimes difficult to purge water from the low spots.
Without a THOROUGH periodic bleed of a DOT5 system, I have and you may eventually see corrosion at the bottom of slave cylinder and caliper bores. I have gone so far as to turn calipers upside down during the bleed process to be sure the water goes out the screws.
Don't get me wrong, I wouldn't use anything else. But do not think it's a fill and forget panacea. Without regular care and maintenance, it can cause some very ugly problems over the long run.
DOT 5
-
Alan Stanyon
- Posts: 34
- Joined: Sat Feb 19, 2011 4:53 pm
Re: DOT 5
Thank you for your insight about the pooling i hadn't thought of that i will bear it in mind perhaps a yearly purge may be in order and i will reassess my fit and forget theory.
Alan
From:
anzhonda600owners@yahoogroups.com on behalf of D & K Grandinett grandinett@... [anzhonda600owners]
Sent:
06 March 2018 15:48
To:
Yahoogroups
Subject:
[anzhonda600owners] DOT 5
I have used DOT5 on all my classic cars for over 40 years primarily because of it's non-aggressive nature towards paint-- bleeding always seems to get fluid on something. However, it is not without it's risks.
It is non-hydroscopic which means it does not absorb water, but that characteristic can be both good and bad. With heat cycling, condensation will almost always show up in brake hydraulics-- DOT 3/4 will hold this water more or less harmlessly in suspension while DOT5 rejects this condensation and allows it to pool in the low spots in the system. Unfortunately, bleed screws are designed to eliminate air which naturally goes to the high points making it sometimes difficult to purge water from the low spots.
Without a THOROUGH periodic bleed of a DOT5 system, I have and you may eventually see corrosion at the bottom of slave cylinder and caliper bores. I have gone so far as to turn calipers upside down during the bleed process to be sure the water goes out the screws.
Don't get me wrong, I wouldn't use anything else. But do not think it's a fill and forget panacea. Without regular care and maintenance, it can cause some very ugly problems over the long run.
Alan
From:
anzhonda600owners@yahoogroups.com on behalf of D & K Grandinett grandinett@... [anzhonda600owners]
Sent:
06 March 2018 15:48
To:
Yahoogroups
Subject:
[anzhonda600owners] DOT 5
I have used DOT5 on all my classic cars for over 40 years primarily because of it's non-aggressive nature towards paint-- bleeding always seems to get fluid on something. However, it is not without it's risks.
It is non-hydroscopic which means it does not absorb water, but that characteristic can be both good and bad. With heat cycling, condensation will almost always show up in brake hydraulics-- DOT 3/4 will hold this water more or less harmlessly in suspension while DOT5 rejects this condensation and allows it to pool in the low spots in the system. Unfortunately, bleed screws are designed to eliminate air which naturally goes to the high points making it sometimes difficult to purge water from the low spots.
Without a THOROUGH periodic bleed of a DOT5 system, I have and you may eventually see corrosion at the bottom of slave cylinder and caliper bores. I have gone so far as to turn calipers upside down during the bleed process to be sure the water goes out the screws.
Don't get me wrong, I wouldn't use anything else. But do not think it's a fill and forget panacea. Without regular care and maintenance, it can cause some very ugly problems over the long run.