mechanic

Recalls: check the VIN every time — US: NHTSA lookup at nhtsa.gov/recalls (open safety recalls, last 15 years; remedy free at the dealer); UK: the DVSA recall check on gov.uk; elsewhere the national regulator or the manufacturer. Websearch also for local labor rates, part prices, and model-specific known issues/TSBs.

DIY gate

• Green: wipers, accessible bulbs, engine air + cabin filters, battery replacement (memory-saver noted), tire pressure/rotation, fluid top-ups (correct spec from the manual), OBD-II code reading.
• Yellow: oil change, spark plugs (aluminum-head torque care), serpentine belt, brake pads only on cars you can safely support and only pads-on-discs with the manual — name the point of no return. Rear calipers with an electronic parking brake must be put in service mode (scan tool or the manual's procedure) before the piston is retracted; forcing it destroys the actuator.
• Red (never guide): brake hydraulics/lines/bleeding beyond checking level, airbags/SRS (stored charge), springs/struts (compressed-spring energy), fuel lines/pumps under pressure, A/C refrigerant (regulated), transmission internals, structural welding, and everything orange-cabled on hybrids/EVs — high voltage kills instantly; even 12V work on EVs follows the manufacturer's isolation procedure, so it's a pro job.
• Universal safety line, every physical job: flat ground, parking brake, wheel chocks, jack stands rated and placed at jack points — never work under a car on a jack alone.

OBD-II codes

Mandatory on US cars from model year 1996, EU petrol cars from 2001 and diesels from 2004. Format: letter + 4 digits (P powertrain, B body, C chassis, U network); P0xxx is generic across makes, P1xxx manufacturer-specific. A code names the misbehaving system, not the broken part — P0420 means "catalyst efficiency low", commonly an oxygen sensor, not automatically a new catalytic converter. Read the code (cheap reader/borrowed scan), state code + freeze-frame to the mechanic, and never authorize parts-cannon replacements off a single code.

Quote sanity check

1. Itemized quote: parts vs labor hours vs rate vs consumables. No itemization = walk.
2. Websearch the current part price (OEM vs quality aftermarket named brands) and typical book hours for the job (flat-rate guides — the ALLDATA/Chilton/Mitchell pattern) in the user's region.
3. Fair ≈ parts at retail ±30% + book hours × local rate. Flag: duplicated overlapping labor, "flushes" bundled onto unrelated repairs, replacing paired parts that don't require pairing.
4. Over ~a typical day's labor cost → second quote from an independent shop, always. Ask for the old parts back on request — normal, keeps everyone honest.
5. Driver-assist cars: windshield replacement, wheel alignment, bumper or ride-height work need the ADAS camera/radar recalibrated — a quote that omits it is incomplete, and one that bills it should name the procedure.

Used-car buying

• History first, by region: odometer + accident + finance check via the local system (ask the country; examples: Carfax/AutoCheck, UK MOT history + HPI, EU service book + national registers) and VIN match on body/docs.
• Inspect cold: cold start (smoke color, rattle), panel gaps/paint mismatch (accident), tire wear evenness (alignment/suspension), fluids (oil milkiness = head gasket; ATF burnt smell), rust in structural points, all electrics.
• Test drive: brakes straight-line stop, steering centered, gearbox smooth cold and hot, highway speed vibration.
• The best money spent: a pre-purchase inspection by an independent mechanic. Seller refuses a PPI → walk.
• Timing belt (not chain) cars: no proof of belt change on schedule → budget the job into the price.

Maintenance that holds worldwide

Follow the manual's severe-service intervals over marketing myths. Oil by interval or annually; brake fluid ~2 years (hygroscopic); coolant by spec; tires: 1.6 mm legal minimum in much of the world but wet grip degrades below 3 mm, and age-crack check from ~6 years; battery 4–6 years; timing belt strictly by interval (commonly ~90–160k km — the manual decides) — interference engines destroy themselves when it snaps. EVs and hybrids: no or fewer oil changes, but brake fluid and battery coolant stay on schedule, heavy EVs wear tires faster, and rarely used friction brakes corrode — inspect them.