ShelfYears

Does carb cleaner expire?

3M gives an unopened can of its throttle plate and carb cleaner 36 months — three times what the same company allows its own brake cleaner — while CRC warrants 2 years from the date code stamped on the bottom.

Updated

Carb cleaner
Sealed
2–3 years
Opened
Same 2–3 years
PROPELLANT LOSS & VALVE CLOG
Degraded performance

Sealed: 2–3 years Tier 1

3M's data sheet: "When stored at the recommended conditions in original, unopened containers, this product has a shelf life of 36 months." CRC's blanket figure is a conditional 2-year warranty from the date of manufacture, repeated on its date-code sheet as a conditional warranted shelf life. The gap between 3M's brake cleaner and its carb cleaner is worth noticing: same company, same shelf, three times the window.

By manufacturer — the disagreement is information
Brand Sealed window
3M Throttle Plate & Carb Cleaner 36 months unopened
CRC 2 years from the date code

After opening: Same 2–3 years Tier 1

The valve reseals after every press, so an aerosol's window runs from the fill date and not from first use. Bulk carb cleaner in a can with a screw cap is the one to watch instead: the solvent evaporates a little at every opening, and what is left behind is a heavier, slower blend than the label describes.

How to tell it's gone off

  • A can that gives a weak fan, a dribble or a hiss in ordinary use instead of a hard, focused stream.
  • The can feels heavy but sprays nothing: propellant escaped, solvent stranded.
  • A varnished or sticky straw and nozzle from the last use, left to harden.
  • Rust or corrosion around the rim, seam or base of the can.
  • Read the date code on the bottom of the can, decoded below, against the maker's window.

If you use it anyway

Degraded performance

If it sprays, it cleans — a carb cleaner's solvent does not deteriorate sitting in a sealed can. Both published numbers describe the container: 36 months unopened from 3M, 2 years from the date code from CRC. Past those the realistic outcome is a can that will not deliver, or delivers a weak dribble where you needed a jet. The cost lands on your afternoon, not on the part.

Why it goes off — PROPELLANT LOSS & VALVE CLOG

The blend itself is stable — a solvent that dissolves varnish is not one that turns into varnish. The failures are all in the package: propellant escaping past the valve seal, a nozzle that crusts over between uses, and a corroding can in a damp corner. Carb cleaners tend to carry heavier aromatic solvents than a brake cleaner does, which is part of why they sit at the long end of the shelf-life range and also why a neglected nozzle gums more readily.

Every page here commits to one of four states — Harmless · Degraded performance · Equipment damage · Safety issue. How the verdicts work.

How to store it

3M asks for two things and nothing more: store the can at room temperature, and rotate stock first-in, first-out so the oldest can goes first. CRC's date code, stamped on the bottom of every aerosol it makes, is what lets you tell which one that is.

Reading the CRC Industries date code

On a CRC aerosol the code is stamped on the bottom of the can. Since July 2007 it reads as five digits: two for the year, then three for the day of that year — 001 is January 1, 035 is February 4, 365 is December 31. CRC publishes the format and its own worked example.

Worked examples
Printed code Made on
07182 July 1, 2007
10035 February 4, 2010

The decoded day is what's printed on the container — it tells you the product's age, nothing about this page. More formats.

Sources