PULSCAR SORTING RULES — TRANSMISSION FLUSH COMPLAINTS (NHTSA, 2015 TO 4 OCTOBER 2026)
Published alongside https://www.pulscar.io/blog/transmission-flush-cost . License: CC BY 4.0.

The rules below were written before any complaint in the set was sorted, and a dated record of these rules was kept before sorting:
2026-11-04T08:28:58Z  (UTC time)
4ee709aa7d05776df48a4e3f3b1974d1adf09de10dc0b16f799459e1e0d2670a  (identifier of the rules file exactly as written)

(Two wording changes were made to the text below for publication: this title, and the heading of the appendix. Nothing else differs from the file as first written.)

POOL HISTORY: the first search (the patterns in the appendix) found 1,005 complaints and was not changed after the rules were fixed.
A separate completeness search, which tried a flush wording far from the transmission wording, misspellings, "fluid exchange" and "exchanged the fluid" wording, repeated drain-and-fill wording with no flush word, cleaning chemicals put through the transmission, and cooler flushes, found 47 more; those were sorted by the same rules, unchanged. Borderline cases the search set aside (plain repeated fluid changes spread over years of ownership, and an additive with a single fluid change) were not added.

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# Sorting rules — transmission flush complaints (transmission-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 contains a flush wording
(flush, flushed, flushing, power flush, and common misspellings) OR a fluid-exchange wording
("fluid exchange", "transmission exchange", "exchanger", "machine flush/exchange") within 120
characters of a transmission wording (transmission, transaxle, trans, CVT, tranny, ATF, torque
converter, DSG, gearbox, TCC, shudder). Exact patterns are in the appendix.
The pool is wide on purpose: it also catches coolant, brake and engine flushes that sit next to a
transmission word. The people sorting decide relevance (N) for every complaint.

"Flush" in this study means a service in which transmission fluid (ATF, CVT fluid, DCT/DSG oil) is
replaced by something other than a single plain drain-and-fill, or is called a flush or
an exchange by the people involved. A single "drain and fill" or "fluid change" that nobody calls a
flush or exchange is NOT in scope (it is N unless the complaint also describes a flush or exchange).

For each complaint record the KIND, WHY, WHO, OUTCOME, UNIT and MILES fields below.

## KIND (one letter) — what job was called a flush or exchange on THIS vehicle

M — Machine, pressure or chemical flush. The complaint says the fluid was exchanged or flushed with a
    machine, exchanger, pressure or "power" flush, "fluid exchange" service, a flush chemical,
    solvent, cleaner or additive put through the transmission (brand names such as BG, Wynn's,
    Valvoline machine count), or a quick-lube/chain "transmission flush" described as a machine job.
R — Repeated drain-and-fill. The complaint says the fluid was drained and refilled more than once
    (for example "triple flush", "three drain and fills", "two fluid changes in a row", "drained
    and filled three times with a drive in between"), by hand/no machine, including a dealer or maker
    procedure defined that way. Not a single drain-and-fill.
U — Unspecified flush. The complaint says the transmission was flushed (or "fluid exchange"
    without a stated method) and done, but not how: no machine, no repeat count.
K — Cooler or line flush in a repair. The only flush stated on this vehicle is a flush of the
    transmission cooler, cooler lines or internals as part of a transmission, converter, cooler or
    radiator repair or replacement (not a fluid service).
Q — Recommended, quoted or declined only. A flush or exchange was recommended, offered, quoted,
    scheduled or refused, and the complaint does not say it was done on this vehicle.
N — Not relevant: not a transmission-fluid flush/exchange on THIS vehicle. Examples: coolant,
    radiator, brake, power-steering, fuel, engine, A/C or oil-system flush; "flush" meaning
    "level with" or "flush-mounted"; a single plain fluid change never called a flush or
    exchange; a flush mentioned only as general advice ("people say you should never flush"), or in
    text pasted from a recall/bulletin with nothing about this vehicle's own history; a flush on
    someone else's car; a transmission word that is unrelated to the flush.

Precedence among done flushes: M, then R, then U, then K. A flush that was done AND another
that was only recommended: code the done one. If the complaint describes a coolant flush and a
separate transmission flush, code the transmission one.

## WHY (one letter) — the stated reason for the flush (for N use X)

B — Maker procedure. The complaint says the dealer or maker did or recommended it under a
    bulletin, TSB, recall, special coverage, warranty or "per GM/Honda/..." procedure, or as the
    maker's fix for a named shudder/judder/software issue.
S — Symptom. Done, recommended or quoted to fix a transmission symptom that already existed
    (slipping, shudder, harsh shift, hesitation, noise, warning light, code), without B.
A — Add-on. The owner says the flush was offered or pushed by a shop or dealer during another
    visit (oil change, inspection, tire/brake work, state inspection, "multi-point") with no
    symptom, or calls it unnecessary or up-sold, without B or S.
P — Preventive. Routine/preventive maintenance: mileage interval, "due", "recommended at X
    miles", "to keep it healthy", before a trip or sale, with no symptom, without B, S or A.
R — Repair step. The flush was part of a transmission, converter or cooler repair or replacement
    (normally with KIND K).
X — Reason not stated.
Precedence: B, then S, then R, then A, then P, then X. (A flush done for a symptom that the dealer
tied to a bulletin = B.)

## WHO (one letter) — who did the flush (or who recommended/quoted it, for Q)
D — Dealer or maker-authorised service department.
S — Other shop: independent mechanic, repair chain, transmission shop, quick-lube or oil-change chain, tire shop.
W — The owner or a friend/family member (do-it-yourself).
X — Not stated. (A "mechanic" or "shop" that is not described as a dealer = S.)

## OUTCOME (one letter) — what the complaint says followed the flush (for Q and N use U)
W — Worse. A new problem, a worse symptom, damage or a failure is said to have begun
    after the flush or because of it ("died 22 hours later", "started slipping after the
    flush", "dealer said the flush caused it"). The owner's attribution counts; the note says
    how the complaint ties it. Words alone about timing count only if the complaint says the
    problem started after the flush.
H — Helped. The symptom stopped or improved, even if only for a while, and W is not stated.
Z — No change. The symptom stayed the same or the flush made no stated difference, W and H not stated.
U — Not stated or not applicable (nothing said about what followed, or the flush was only recommended).
Precedence: W, then H, then Z, then U. (Improved for a month and then failed worse = W only if
the complaint blames the flush; otherwise H.)

## UNIT (yes/no)
yes — the complaint says the transmission or transaxle was replaced, rebuilt or remanufactured, or
that replacement/rebuild was recommended or quoted, at any point in the story (before or after
the flush; both count). no otherwise, and for N.

## MILES (integer or 0)
The odometer reading when the flush was done, if the narrative states it (digits only, no
commas, "k" expanded: 85k = 85000). 0 if not stated. Use the odometer at the flush, not at the
complaint, and not a service interval. For N and Q write 0.

## Output
One line per complaint, comma-separated, no header, in the order given:
`odino,kind,why,who,outcome,unit,miles,note`
kind is one of M R U K Q N; why one of B S A P R X; who one of D S W X; outcome one of W H Z U;
unit yes/no; miles an integer. For N write `N,X,X,U,no,0`.
note: at most 15 words, no commas (use semicolons), naming the evidence.

## Appendix — exact pool patterns (Python re module, case-insensitive)
```
F = fl[uo]sh\w* | flsuh\w* | fushed | power\W?flush
E = (?:fluid|atf|trans\w*)\W+(?:exchange|exchanger|exchanged)
    | (?:exchange|exchanged)\W+(?:of\W+)?(?:the\W+)?(?:trans\w*\W+)?(?:fluid|atf)
    | fluid\W+machine | machine\W+(?:flush|exchange)
T = transmission | transaxle | \btrans\b | \bcvt\b | tranny | \batf\b | torque\W{0,3}conv | \bdsg\b | gearbox | trans\. | \bTCC\b | shudder
Rule: a match of F or E whose window of 120 characters on either side contains a match of T.
```

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TIE-BREAK RULES, written while the first 164 disagreements were read and extended as later ones were settled (R12 to R19 were added in the course of the work; rule_applied in the complaints file names the rule used):
R1  KIND K vs U. K only if the complaint says the COOLER, cooler lines, converter or other internal parts were flushed. If it says the transmission (or its fluid) was flushed, the kind is U (or M/R when the method is stated), even when the flush was done in a repair (radiator replaced, coolant in the fluid, rebuild) - then WHY = R. A rebuild or replacement that mentions "flush" only in the same breath as the cooler or lines = K.
R2  KIND R needs an explicit count of two or more fills/changes/flushes of the fluid ("triple flush", "three drain and fills", "done twice"); "flushed again after it came back" is two separate services, code the one described in detail as U and say nothing more. A single "drain and flush" = U.
R3  KIND M needs a machine/exchanger/pressure/chemical wording in the complaint. "Dealer flush" alone is U.
R4  KIND Q vs U vs N: a flush only recommended, quoted, scheduled or refused = Q; the complaint's own words "had it flushed/was flushed" = done = U (or M/R); a flush mentioned only as something the owner thinks should be done, or advice to others = N.
R5  WHO D only if the text says dealer/dealership/"authorized"/the maker's service department, or uses the standard NHTSA complaint phrase "taken to a (local) dealer"/"the dealer" for the flush visit. "Under warranty", "the manufacturer" or "service center" alone = X. A named independent/chain/quick-lube/"mechanic"/"shop" = S. Owner or relative did it = W.
R6  WHY S needs a transmission symptom (slip, shudder, harsh shift, noise, warning, no-go) stated before the flush AND the flush offered/done for it or listed among the fixes tried for it. A symptom in the complaint with no link to the flush = X. WHY B needs the dealer/maker to cite a bulletin/TSB/recall/program/"per GM", or "under warranty for the judder/shudder" with a maker procedure stated; plain "under warranty" with a symptom = S. WHY R when the flush was done during a repair of another part (radiator, cooler, rebuild); WHY A when pushed during another visit; P for stated routine/preventive/mileage service.
R7  OUTCOME W: the complaint says the problem/failure began after the flush, or a failure is stated to have followed within the same story (hours, days, weeks) with no earlier symptom, or the dealer/shop is said to blame the flush. "Became more frequent/worse soon after" = W. A transfer-case or other part's failure after a flush counts only if the owner links it in the text; mere timing in one sentence ("flushed 2 weeks before it exploded") = W (the sorting rules counts stated timing).
R8  OUTCOME Z: a symptom existed, the flush was done, and the complaint says it continued/persisted/returned or that nothing changed, without a worse state. H: the complaint says it helped/improved/fixed, even briefly; if it then came back, H (not Z) unless R7 applies. U: no result stated, flush only recommended, or the story moves to another repair without a stated effect of the flush.
R9  UNIT yes: transmission/transaxle replaced, rebuilt or remanufactured, or replacement/rebuild recommended or quoted, at any point. Converter-only replacement, valve body, solenoid, cooler = no. "Replacement told/advised for the converter" = no. A new transmission half-covered by the maker = yes.
R10 MILES: the odometer reading when the flush was done. If a number is attached to the flush visit ("at 105k took it in for the flush"), use it. A complaint mileage with no link to the flush = 0. Two numbers: take the one linked to the flush.
R11 N: choose N only if no transmission-fluid flush/exchange on THIS vehicle is described or recommended. If the complaint recommends/quotes one it is Q, not N.
R12 MILES: a typed odometer that is not plausible for the flush visit (for example "10205" for a "100,000 mile service", or fewer than 1,000 for a car older than a year) = 0. Use the figure only when it is clear.
R13 (clarifies R7) OUTCOME W requires that the complaint ties the new/worse problem to the flush itself or says it began after the flush with no other stated cause. If the text says the failure came from another stated cause (a radiator leak, contaminated fluid, a failed part, the original fault) it is not W: use Z if the original symptom persisted, else U. Timing alone, in a story that already names another cause, is not W.
R14 WHY R applies when the flush is part of a repair of another part (radiator, cooler, rebuild) per R1/R6; where a symptom drove the repair, still R.
R15 (from reviewer a3) A store named with a maker brand and a dealer-group name ("Autonation Buick GMC") is a dealer: WHO = D.
R16 (from reviewer a3) An odometer given in kilometres is not converted: MILES = 0.
R17 (from reviewer a4) A flush listed among fixes tried while the problem is described as ongoing, without a sentence saying the symptom continued after the flush, is OUTCOME U, not Z.
R18 (from consistency reviewer 2) A store named with a maker brand plus a place or person name ("Conyers Nissan", "Crown Acura", "Tucker Chevrolet") is a dealer: WHO = D. "Subaru service", "Acura service", "Nissan service center" = D. A bare maker name ("took it to Ford", "Honda recommended"), "warranty work" or "recall repair" = X.
R19 (from consistency reviewer 2) A flush "and conditioning treatment" or any additive/cleaner put through the transmission = KIND M.


CONSISTENCY PASS: complaints on which both sortings agreed were checked against the rules by a keyword test that flagged 150 complaints as possibly inconsistent; each flagged complaint was read, and for 48 of those that both sortings had agreed on the code was corrected (rule_applied shows the rule and the reason).