PULSCAR SORTING RULES - BRAKE FLUID SERVICE COMPLAINTS (NHTSA, 2015 TO 4 OCTOBER 2026)
Published alongside https://www.pulscar.io/blog/brake-fluid-flush-cost . License: CC BY 4.0.

Rules dated and fixed before any complaint was sorted:
2026-11-04T08:30:36Z
d663745e7155588bfa3b256f1e3bba21f051f7aac4645af675e61e06573145b0  (fingerprint of the rules text as first written; the text below differs from it only in wording changed for publication, such as the title)

POOL HISTORY: the first search (the four patterns in the appendix) found 1,719 complaints and was not changed after the rules were fixed. A second, wider search of the whole complaint file (looser wording: bled/purged/flush/exchange/refill phrased away from the words "brake fluid", DOT grades, moisture and boiling-point words, brake service and interval wording; 4,334 narratives with brake wording and a fluid, bleed or flush word near it) was read in full for what the first had missed and added 317 more, which were sorted by the same rules without change. found_by in the complaints file says which search found each complaint.

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# Sorting rules — brake fluid service complaints (brake-fluid-flush-cost study)

Written before any complaint in the set was sorted.

## Pool (how the complaints were found)
NHTSA complaints received 2015-01-01 to 2026-10-04 (782,908 narratives, NHTSA flat files
downloaded 07.10.2026). A complaint is in the pool if its narrative matches any of four
case-insensitive patterns (A, B, C, D; exact patterns in the appendix of this file):

A. "Brake fluid" (or "brake oil") within six words of a service or condition word (change, flush,
   bleed/bled, exchange, replace, service, drain, top off/up, add, fill, refill, interval,
   maintenance, schedule, moisture, water, contaminated, old, dark, dirty, boil, absorb,
   hygroscopic, wrong, incorrect, DOT, mix, degraded, brown, black, rust, corrosion, cloudy,
   milky, burnt, fresh, new, expired), in either order.
B. A brake service phrase: "brake flush", "brake system bleed", "brake exchange", "flushed the
   brakes", "bled the brakes", "brakes were bled/flushed".
C. "DOT 3", "DOT 4", "DOT 5" (also "DOT 5.1").
D. "Moisture" or "water" within six words of "brake fluid", "brake line" or "brake system".
The pool is wide on purpose: owners rarely use the words a shop uses. The people sorting decide
relevance (N) for every complaint.

For each complaint record exactly one CATEGORY and four yes/no FLAGS.

"Brake fluid" here means the hydraulic fluid of the vehicle's service brakes (glycol-ether DOT 3,
DOT 4, DOT 5.1, silicone DOT 5, or the maker's own brake fluid). It does NOT include clutch-only
hydraulic fluid, power-steering fluid, transmission fluid or coolant. "A brake fluid service"
means any of: flush or full fluid exchange, fluid replacement/change, bleeding the brakes
(air or old fluid pushed out through the bleeders), top-up or adding fluid, setting or checking
the level, or testing the fluid (moisture or copper test).

## RELEVANCE

N — Not about brake fluid service, condition or type on THIS vehicle. Examples of N: the vehicle
    is not a car, truck, SUV or van (motorcycle, scooter, ATV, trailer, bus, tractor); the
    match is another fluid (clutch fluid only, power steering, coolant, transmission); brake
    fluid is mentioned only as LEAKING from a part (master cylinder, caliper, hose, line,
    wheel cylinder, booster), a low warning light, or a failed part, with no flush, bleed,
    top-up, level check, condition finding, fluid-type statement or recommended/quoted
    fluid service; the narrative is about a brake part replacement and the only brake-fluid
    wording is boilerplate ("replaced pads and rotors and did a brake service") with no
    brake fluid, flush or bleed named; a general remark not about this vehicle. A brake fluid
    service, level check/finding, top-up, bleed, recommendation or quote of a flush, a
    fluid-condition finding, a wrong-fluid statement or a maker interval statement about THIS
    vehicle makes the complaint NOT N, even if the rest of the complaint is about something else.

## CATEGORY (one letter) — the brake-fluid event the complaint describes on this vehicle

W — Wrong fluid or a service done wrong. The complaint states that the wrong type or grade of
    fluid was put in (for example DOT 5 into a DOT 3/4 system), fluids were mixed, the reservoir
    was overfilled, fluid was put in the wrong place, air was left in the system or the brakes
    were not bled properly after a service so the pedal went soft or the brakes failed, a
    bleeder/cap/plug was left loose or missing, or a shop/dealer/maker says a fluid service was
    done incorrectly. Counts when the owner, a shop, a dealer or the maker states it (an owner's
    bare suspicion without evidence does not count).

F — Flush, exchange or fluid replacement performed. The fluid was "flushed", given a "brake
    flush", "fluid exchange", "fluid replacement", "fluid change", "new brake fluid" or "fluid
    was replaced" as a service (alone or with other work), without W. A complaint where a
    flush/fluid replacement is part of a larger repair (master cylinder, caliper, hoses) is
    still F only if the narrative says the fluid itself was flushed, replaced or changed;
    "bled" alone is B.

B — Bled only. The brakes were bled (air removed) as a repair step, after a part replacement or
    to cure a soft or spongy pedal, with no statement that the fluid was flushed or replaced as
    a service, without W or F.

T — Top-up or level. The fluid level was checked and found low, high or correct by a shop, dealer
    or owner, OR fluid was added, topped off or drained down to level, without W, F or B.
    (A leak complaint where the owner simply topped off fluid is T.)

C — Condition or type only. The fluid was found or said to be contaminated, old, dark, dirty,
    brown, milky, wet, with moisture or water in it, boiled or fading, OR the owner states the
    fluid type or grade (DOT 3/4/5) or the maker's required type, without any of W, F, B or T.

R — Recommended, quoted, scheduled or refused only. A dealer, shop or maker recommended,
    quoted, scheduled, prescribed (for example in a bulletin or the maintenance schedule) or
    refused a brake fluid service or stated a service interval for THIS vehicle, or the owner
    asked for one, but the complaint does not say one was performed; without W, F, B, T or C.

Precedence when more than one fits: W, then F, then B, then T, then C, then R.
(A complaint describing a flush AND a later bleed is F; a top-up AND a recommended flush is T;
a flush performed because the fluid was found dark is F.)

## FLAGS (yes/no)

fix_attempt — a fluid service (any of F, B, T, W) was performed, or one was recommended or
    quoted (R), as a remedy or diagnostic step for a brake symptom that already existed (soft,
    spongy or sinking pedal, long pedal travel, pulsation, noise, ABS/brake warning light,
    brakes fading or failing). "no" for routine maintenance, mileage- or age-based services,
    services done before any symptom, and for C.

helped — the complaint says the fluid service or bleed fixed, improved or temporarily relieved
    the brake symptom ("pedal firm again", "better for a week"). "no" when it did not help,
    when the outcome is not stated, or when no service was performed.

worse_after — the complaint states that a brake problem began, got worse, or the brakes failed
    AFTER a fluid service or bleed, and ties it in time to the service ("after the flush",
    "since the fluid change", "two days after", "on the way home from the shop"). An owner's
    general belief that fluid services damage brakes, without a time link to a service on this
    vehicle, is "no".

part_replaced — the complaint says a brake hydraulic or ABS part (master cylinder, caliper, wheel
    cylinder, hose, brake line, ABS hydraulic unit/modulator, booster) was replaced, or a shop
    or dealer diagnosed one as needing replacement or quoted one. Pads, rotors, drums and shoes
    alone are "no".

## Output
One line per complaint, comma-separated, no header, in the order given:
`odino,category,fix_attempt,helped,worse_after,part_replaced,note`
category is one of N W F B T C R; flags are yes or no; for N write no for all four flags.
note: at most 15 words, no commas (use semicolons), naming the evidence (e.g.
"dealer flush at 60k; pedal firm after; no part").

## Appendix — exact pool patterns (Python re module, case-insensitive)
```
BF = brake\W+(?:fluids?|oil)
SV = (?:chang\w*|flush\w*|bleed\w*|bled|exchang\w*|replac\w*|servic\w*|drain\w*|top(?:ped|ping|s)?\W*(?:it\W*|them\W*)?(?:off|up)|add(?:ed|ing|s)?|fill\w*|re-?fill\w*|interval|maintenance|schedul\w*|moisture|water|contaminat\w*|old|dark|dirty|boil\w*|absorb\w*|hygroscop\w*|wrong|incorrect|dot|mix\w*|degrad\w*|brown|black|rust\w*|corros\w*|cloudy|milky|burnt|burned|fresh|new|expire\w*)
W  = \W+(?:\w+\W+){0,6}?
A = \bBF W SV\b | \bSV W BF\b
B = \bbrakes?\W+(?:system\W+|lines?\W+)?(?:flush\w*|bleed\w*|bled|exchang\w*)
    | \b(?:flush\w*|bleed\w*|bled)\W+(?:\w+\W+){0,3}?(?:the\W+|all\W+|my\W+|their\W+)?brakes?\b
    | \bbrakes?\W+(?:were|was|had been|have been|got)\W+(?:\w+\W+){0,2}?(?:bled|flushed)
C = \bDOT\W?[345](?:\.1)?\b
D = (?:moisture|water) W brake\W+(?:fluid|line|system) | brake\W+(?:fluid|line|system) W (?:moisture|water)
```

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TIE-BREAK RULES, written while the first 93 disagreements were read and extended as later ones were settled; rule_applied in the complaints file names the rule used for each complaint settled by one:
R1  A contact-template narrative "the dealer diagnosed that the brake fluid needed to be changed/flushed/replaced ... the vehicle was repaired" = F (a fluid service was done; the repair is the diagnosed work). helped=yes only when the fluid service alone is the diagnosed fix; when the list also names parts (cylinders, hoses, calipers, pads) helped=no and part_replaced=yes.
R2  helped=yes only when the narrative states relief (brakes worked, pedal returned, car driven on, "repaired") even if the problem later returned; helped=no when the only outcome stated is that the symptom persisted, fluid drained again, or nothing is said. A top-up that lets the owner drive to a shop = yes.
R3  A bleed or fluid change that was planned, attempted with nothing flowing, or only intended by the owner (no shop or maker asked or quoted) = N unless a level check/top-up is described (then T).
R4  worse_after=yes only when a person (owner, shop, dealer, maker) ties a new or worse failure to a fluid service; if the failure comes from a part or leak that existed before the service (leak, failed line, HCU) = no, even if the pedal fails right after a top-up or during the test drive of a bleed.
R5  fix_attempt=yes when a top-up, bleed or flush was done because of a symptom already present (low-fluid warning, soft pedal, level falling, failed brakes), including a flush done as part of repairing a brake fault; no for routine/before-symptom services.
R6  A gas or foreign substance reaching the fluid because a part failed (booster nitrogen, ABS pump leak) is a part failure = N unless a service on the fluid is described.
R7  A dealer estimate or invoice line that lists "bleed brake system" with a part replacement, with no statement it was done = R (quoted/prescribed); stated as done = B.
R8  A maker procedure the owner complains about (a scan tool is required to bleed the ABS) = R (prescribed procedure for this vehicle).
R2b helped=yes needs an explicit word of relief ("repaired", "fixed", "worked", "felt good", "light went off", "held", "drove home ok"); "the same problem happened again/a week later" with no earlier relief word = no.
R9  part_replaced=yes when a hydraulic or ABS part was replaced, or a shop/dealer diagnosed it as failed, leaking or worn, or quoted it; an owner's own plan or guess = no.
R10 A reservoir found low or empty by the owner or a dealer = T (level finding) even with no fluid added; fix_attempt=yes only if fluid was added or a service done for a symptom.
R11 W needs a statement that a service was done wrong (wrong fluid, air left by the shop, loose plug). An owner whose own bleed did not cure a soft pedal (air trapped, unit at fault) = B. A dealer that only "suspects" faulty earlier service = F, not W.
R12 A grade (DOT 3/4) named only as part of a recalled, prescribed, scheduled or refused change that was not done = R (the event is the service not done); C when the grade or condition is itself the finding (fluid blamed, old DOT 3 left in the system, contaminated); fix_attempt=no for C.
R13 A complaint about a service that was NOT done (e.g. "the dealer did not top off the fluid at maintenance") with no level finding, quote or maker interval = N.
R2c (replaces R2b) helped=yes when the narrative has a relief word OR states a period/distance of normal operation after the service ("a week later", "for two weeks", "next day", "10 miles later"); no when only "again" with no period, or the outcome is not stated.
Consistency pass: agreed worse_after=yes rows were read (47); five where the failure was the same pre-existing fault coming back after a bleed or top-up were changed to no (R4).


CONSISTENCY PASS: complaints on which both sortings agreed were read where the flag worse_after said yes (47 in the first search, 16 more in the second); five were changed to no under rule R4 (rule_applied shows it).