Editorial Policy
This page sets out how technical content on GM Service Guy is researched, sourced and corrected. It exists so you can judge whether to trust a page here, rather than having to take its word for it.
Who writes this
Technical articles are written by Allen McCormick, who has worked with General Motors vehicles since 2007 — Chevrolet sales in Saskatoon and Las Vegas, then service advisor roles, and a service advisor at Fairway Chevrolet since 2021.
Where the technical information comes from
GM documents are the primary source. Diagnostic articles are built from GM technical service bulletins, preliminary information documents, special coverage notices and emission recalls. Where those documents are publicly hosted by the National Highway Traffic Safety Administration, they are linked directly so you can read them yourself.
Bulletins are opened and read, not summarised from a lookup. Code-lookup databases frequently associate a bulletin with a diagnostic trouble code that the bulletin does not actually mention. Before a bulletin is cited here, the document itself is checked to confirm it names the code and covers the vehicle under discussion.
Vehicle coverage is stated, including when it does not match. A bulletin written for a Colorado is not presented as Equinox guidance. Where a document is included because its failure mode is instructive rather than because it applies to the vehicle in the title, the article says so plainly.
Verified and corroborated are distinguished. Where a specification was read in GM's own document, the article says verified. Where it comes from technicians or secondary sources that could not be confirmed against the original, it says corroborated. These are not treated as equivalent.
What gets removed
Claims that cannot be supported are removed rather than softened.
That includes part numbers with no traceable source, specifications carried over from a different engine or model, bulletin citations that turn out not to cover the code in question, and fitment claims that do not hold up against the manufacturer's own documentation.
Word count is not treated as a quality measure. Some subjects have less documented material than others, and an article that is shorter because the sourcing is honest is preferable to one padded to a target length.
How corrections are handled
Corrections are published on the page, not made silently. When an article is found to be wrong, the correction is written into the article itself, stating what the earlier version said and why it was removed. The article is not quietly edited as though the error never happened.
Several articles on this site carry corrections of this kind — including engine oil specifications that were wrong for the engine in question, a part recommended for an engine family it does not fit, and a repair recommended where the manufacturer routes the diagnosis differently. Those corrections stay visible.
If you find something wrong here, email allen@gmserviceguy.shop. Corrections that hold up get made and credited on the page.
Products in articles
GM Service Guy is a parts and accessories retailer, so articles link to products sold here. Some things follow from that which are worth stating.
Fitment is checked against the catalogue, not assumed. Products are linked because the listing states they fit the vehicle being discussed. Where a listing carries an exclusion — a body style, an engine, a build date range — the article repeats it.
Gaps are named. Where the correct part for a vehicle is not stocked here, the article says so and tells you to buy it elsewhere rather than substituting something that nearly fits. That has happened on several pages, and it will keep happening.
Diagnosis comes before parts. Articles are ordered by what to check first, not by what is most expensive to sell. Where a free check can rule out a costly repair, the free check goes first.
What this site does not do
GM Service Guy sells parts and accessories. It does not perform repairs, book service appointments or operate a service facility.
Articles here are reference material, not a substitute for diagnosis on your specific vehicle. Safety-related systems — brakes, restraints, steering, fuel and emissions — should be worked on by someone qualified to do so. Where a repair involves airbags, fuel systems or emissions equipment, the articles say so.
Warranty coverage, recall involvement and special coverage eligibility are determined by VIN through a dealer, not by a model-year table on a website. Where an article discusses coverage, it explains how to check rather than telling you that you qualify.
Prices and availability
Prices quoted in articles are starting prices at the time of writing and change with variant and availability. The product page is authoritative. Always confirm fitment against your own VIN before ordering.
Contact
Questions, corrections and fitment queries: allen@gmserviceguy.shop