The Car Gear Numbers
Car gear is sold on big numbers — peak amps, mAh, "10-in-1" claims — that mean very little without context. This page is the normalized reference: every spec number worth knowing before buying jump starters, OBD2 scanners, motor oil, wiper blades, tire gauges, floor mats, or batteries, what it actually measures, and where it comes from. It is a reference dataset, buying-guide and spec framing only — not repair or safety instructions. Always follow your vehicle's owner's manual for procedures.
The one thing to know: A jump starter's advertised 'peak amp' number is a manufacturer marketing figure — a brief burst rating, not a sustained cranking-amp guarantee, and it is not standardized the same way across brands. What actually predicts whether a pack can start your engine is a combination of its real (not peak) output, its battery capacity in Wh, and your engine's displacement and cranking-amp requirement — cross-check independent reviews and the maker's own engine-size chart rather than comparing peak-amp numbers between brands as if they were equivalent.
The decoder table
| Spec / claim | What it actually means | Source |
|---|---|---|
| Jump starter peak amps | A brief-burst manufacturer marketing rating, not a sustained cranking-amp guarantee; not standardized across brands. | Manufacturer spec sheets; cross-checked against independent reviews |
| Jump starter mAh vs Wh | mAh only means something at a stated voltage; Wh (V x Ah) is the true comparable energy-capacity unit across different packs. | Battery engineering fundamentals (V x Ah = Wh) |
| OBD2 basic code reader | Reads/clears generic (P0xxx) engine powertrain codes only. No ABS, SRS, or body-module access. | SAE J1979 / J2012 generic OBD2 scope |
| OBD2 live-data scanner | Adds real-time sensor graphing (RPM, O2, coolant) but stays engine-system only unless make-specific software is included. | Manufacturer tool documentation |
| OBD2 full-system / bi-directional scanner | Reaches ABS, SRS/airbag, transmission and other modules, and can command bi-directional actuation tests — but only for vehicles in the tool's specific make/model/year coverage list. | Manufacturer coverage lists; verify per vehicle before buying |
| OBD2 protocols | Five recognized OBD2-era protocols: SAE J1850 PWM (Ford), SAE J1850 VPW (GM, ~1996-2003), ISO 9141-2 (Chrysler/European/Asian imports, ~1996-2004), ISO 14230-4 / KWP2000 (European), and ISO 15765-4/SAE J2480 (CAN, standard on all vehicles 2008+ in the US). | SAE J1850, ISO 9141-2, ISO 14230-4, ISO 15765-4 standards |
| Motor oil 'W' number (e.g., the 5 in 5W-30) | Winter viscosity rating — describes cold-flow performance at low temperature. Lower number flows more easily when cold. Not a quality or brand claim. | SAE J300 viscosity grade classification |
| Motor oil second number (e.g., the 30 in 5W-30) | Kinematic viscosity at 100°C (approximate normal operating temperature). Higher number stays thicker at operating temperature. | SAE J300 viscosity grade classification |
| API SP / SN service categories | Current API gasoline-engine oil service categories (SP is the latest as of this writing) covering wear, deposit, and additive performance standards. Diesel engines use a separate API category (e.g., CK-4) — not interchangeable. | American Petroleum Institute (API) Engine Oil Licensing and Certification System |
| Synthetic vs blend vs conventional oil | Marketing/formulation categories, not standardized certifications — a synthetic and a conventional oil can carry the identical API SP rating; the base stock affects longevity and cost, not the certified performance category. | API service category documentation |
| Wiper blade sizing method | Correct method is the vehicle owner's manual or a manufacturer/retailer year-make-model lookup tool — not measuring the old blade (which may already be wrong) or guessing. Front driver/passenger blades are often different lengths from each other and from the rear blade. | Wiper manufacturer fitment guides |
| Wiper blade format: beam vs conventional vs hybrid | Beam = frameless single flexing spine, resists ice jamming in joints. Conventional = jointed metal frame, lowest cost, joints can freeze. Hybrid = aerodynamic housing over a beam-style spine, reduces high-speed wind lift. | Wiper manufacturer product documentation |
| Digital tire gauge accuracy | Commonly advertised around ±1 PSI (manufacturer claim, not independently certified per unit). | Manufacturer product specifications |
| Dial tire gauge accuracy standard | ANSI B40.1 defines a named pressure-gauge accuracy grade system (e.g., Grade B) that some dial gauges are built to meet. | ANSI B40.1 pressure gauge standard |
| Pencil (slide-scale) tire gauge | Mechanical, no battery required; generally considered less precise than digital or ANSI-graded dial gauges due to the small extending-pin mechanism and printed scale. | Product design comparisons; manufacturer documentation |
| TPMS (Tire Pressure Monitoring System) | Built-in vehicle system using in-wheel sensors; triggers a dashboard warning once a tire is meaningfully underinflated below the vehicle's placard PSI. It is a low-pressure ALERT, not a precise routine PSI readout — a handheld gauge is still needed for exact checks. | Federal Motor Vehicle Safety Standard (FMVSS) No. 138 (US TPMS mandate, phased in 2007-2008) |
| Floor mat fitment: universal vs custom laser-fit | Universal = generic trim-to-fit shape for broad compatibility. Custom/'laser-fit' = digitized scan of one specific year/make/model/trim's floor pan, typically locking into factory anchor points. | Floor mat manufacturer product documentation |
| Battery BCI group size | A Battery Council International standard describing only physical case dimensions and terminal layout/position — NOT a power rating. Two batteries in the same group can have very different CCA. | Battery Council International (BCI) group size standard |
| Cold Cranking Amps (CCA) | The amps a 12V battery can deliver at 0°F (-18°C) for 30 seconds while holding at least 7.2 volts. The power spec — matched separately from group size (fit). | SAE J537 / BCI battery testing standards |
| Tire tread depth legal limit (US) | 2/32 of an inch is the widely-adopted federal/state legal minimum for passenger tires (a small number of states set a different threshold). Tires have molded wear-bar indicators at exactly 2/32 in. | NHTSA / state DOT tire safety guidance |
| The penny test | Insert a penny with Lincoln's head pointing down into a tread groove. If tread still covers part of the head, more than 2/32 in remains. If the full head is visible, the tire is at or below the legal minimum. | NHTSA consumer tire safety guidance |
| LED vs halogen headlight bulb legality | In the US, replacing a halogen headlight housing with a plug-in LED bulb not originally DOT/SAE-approved for that housing can fail state inspection or violate FMVSS 108 photometric requirements, even though the bulb itself is legal to purchase. Check your state's specific inspection rules and use only bulbs listed as legal for your exact housing. | FMVSS 108 (federal lighting standard); state vehicle inspection codes vary |
Caveats — read before citing a number
- Peak-amp and "stage count" marketing numbers are not standardized across brands the way an SAE, API, ANSI, or BCI standard is — treat manufacturer-only claims with more caution than a named third-party standard.
- OBD2 full-system coverage is a per-vehicle list, not a universal guarantee — always check your exact year/make/model against the specific tool's supported list.
- This table is general spec reference, not a repair or safety procedure for any specific vehicle. Follow your owner's manual for maintenance and repair steps.
- Standards get revised. SAE, API, ANSI and BCI specifications are periodically updated; this dataset reflects the standards as understood as of the version date below.
Methodology & versioning
Version 1.0 — published July 30, 2026. Facts are drawn from SAE (J300, J537, J1850, J1979, J2480), API's Engine Oil Licensing and Certification System, ANSI B40.1, ISO (9141-2, 14230-4, 15765-4), Battery Council International (BCI) group size standards, NHTSA/FMVSS tire and lighting guidance, and manufacturer specification sheets, cross-checked against our existing spec-by-spec guides. We do not physically test products ourselves; this is a specification-facts reference, not a lab result. Corrections: if a standard's scope changes or we find an error, this page and the CSV below are updated in place and the version/date bumped — see How We Evaluate for our full editorial policy.
License: CC BY 4.0 — free to use with attribution. How to cite: Garage Lab (2026). "The Car Gear Numbers." https://garage-lab.pages.dev/car-gear-numbers/.
Machine-readable download: the full table is available as CSV at /car-gear-numbers.csv (versioned copy: /car-gear-numbers-v1.0.csv), and a condensed digest is maintained in /llms-full.txt.
This page is general specification reference, not a repair, safety, or health determination for your specific vehicle. Follow your owner's manual for any maintenance procedure.
Frequently Asked Questions
A normalized reference table decoding the specification numbers that actually matter when buying car care and automotive accessories — jump starter amps, OBD2 scanner tiers, motor oil grades, tire gauge accuracy, battery ratings, and tread depth limits — with a source for each row. It exists because most product listings print a big number without explaining what it measures or guarantees.
No. Peak amps is a brief-burst manufacturer marketing figure, not standardized the same way across brands, and it is not the same measurement as a battery's Cold Cranking Amps (CCA) rating. Match a jump starter to your engine using the maker's own engine-size chart and independent reviews, not by comparing peak-amp numbers between brands.
Only if it is specifically built as a full-system or bi-directional scanner AND your exact vehicle is on that tool's supported coverage list. Basic code readers and most live-data tools are engine-system only. Always check the coverage list for your specific make/model/year before assuming ABS/SRS support.
No. This table normalizes what industry-standard specs and ratings generally mean. Your owner's manual is always the authority for the exact grade, size, torque, or procedure your specific vehicle requires — follow it for any maintenance or repair decision.