PULSCAR ANALYSIS - TRANSMISSION FLUSHES IN NHTSA'S PUBLIC FILES
PulsCar analysis of NHTSA public data, November 2026.
License: CC BY 4.0
Attribution: "PulsCar analysis of NHTSA public data, November 2026."
Published alongside https://www.pulscar.io/blog/transmission-flush-cost

Scope. Complaints NHTSA received from 1 January 2015 to 4 October 2026 (the latest received date in the public files; 782,908 records), the index of manufacturer communications, the recalls table, and manufacturer documents downloaded from static.nhtsa.gov. The complaint file is public: anyone can download it from NHTSA and check any number here against it.

1. Complaints (1,052).
   First search (1,005): every complaint whose narrative contains a flush wording (flush, flushed, flushing, power flush, common misspellings) or a fluid-exchange wording (fluid or transmission exchange, exchanger, machine flush or exchange) within 120 characters of a transmission wording (transmission, transaxle, trans, CVT, tranny, ATF, torque converter, DSG, gearbox, TCC, shudder). The exact wording is in codebook.txt.
   Independent check (47): a separate search of the whole file for what the first one missed (a flush wording far from the transmission wording, misspellings, "exchanged the fluid", repeated drain-and-fill wording with no flush word, cleaning chemicals put through the transmission, cooler flushes). Borderline cases it set aside were not added. found_by in the complaints file says which search found each complaint.
   Sorting. The sorting rules (codebook.txt) were written and dated before any complaint was sorted. Each complaint was sorted twice by written rules, independently, on six points: kind of flush (machine; repeated drain-and-fill; flush with the method not stated; cooler or line flush in a repair; recommended, quoted or refused only; not about a transmission flush on this vehicle), stated reason, who did it, what followed, whether the transmission was replaced, rebuilt or recommended for replacement, and the odometer reading at the flush if the narrative gives one. Where the two sortings differed, the case was settled by a written tie-break rule listed in codebook.txt; the rule applied is in the rule_applied column. A consistency check then reread the complaints flagged by a keyword test.
   Result: 954 complaints about a flush on the owner's own vehicle, or one recommended, quoted or refused for it; 98 not relevant. Counts are counts of complaints, not cars. A complaint is evidence that an owner wrote to NHTSA; nothing here is a failure rate.

2. Documents (see documents.csv).
   Manufacturer communications in NHTSA's index whose own text, in files already downloaded, names a flush or fluid exchange next to a transmission word; a separate search of the index added further documents, which were downloaded and read, and two recall campaigns. For each, documents.csv gives the document, its number as printed, whether the file was read in full or compared with a near copy, whether it names a flush, and its relevance (DIRECT: prescribes, limits or forbids a transmission flush or exchange; PROCEDURE: a repair procedure that includes a flush of fluid, cooler or lines; RELATED; NOT RELEVANT). Vehicle years, engines, build dates and coverage terms are as printed in the documents, never from NHTSA's index. Coverage status "as of September 2026" is the authors' computation from printed terms. Three index entries have no file on NHTSA's servers and are listed with an empty address.

3. Owner-reported amounts (236 figures in 166 complaints).
   One written inclusion rule: a dollar figure is included when the owner states it as a price, charge, bill or quote for flushing the transmission or for transmission work on this vehicle (a flush, a flush bundled with other named work, a cooler or line flush in a repair, a replacement or rebuild, a part or software, a repair not specified, a diagnosis, or a tow caused by the event). Excluded: mileage, vehicle value and payments, repairs of unrelated systems, restatements, other people's costs. Status comes from the owner's words (paid, billed, quoted, offered, not stated). Figures are what owners wrote, not audited invoices.

4. Limits.
   The complaint file holds the cases where an owner wrote to NHTSA, with no verification; owners whose trouble ended are mostly not in it. Most narratives say only that the transmission was "flushed", so the data cannot tell a machine flush from a drain-and-fill that someone called a flush. Only a minority give the odometer reading at the flush. The document set holds what NHTSA's index lists and what could be read; a maker paper that is not in the index is not in it. Shop prices were not collected: the pages we could read show no base price.