Dad’s short answer: On some machines, effectively yes — and it's worth knowing before you buy. Check formula availability the same way you'd check replacement parts, because a machine tied to a formula your local store doesn't stock is a machine you'll struggle to run.

Where lock-in is real

Some manufacturers design the machine around their own formula and specify it exclusively. On one upright I tested, it only runs the brand's two formulas, and at the time those weren't on every store shelf yet. That's not a dealbreaker, but it belongs in your buying decision, because running out mid-job means you're ordering online and waiting.

Other machines are open about it and work fine with any compatible extractor solution. Those give you more choice and usually a lower ongoing cost.

Check three things before you buy: which formula the manual specifies, whether you can actually buy it locally, and whether using something else voids the warranty. That last one is the part people discover too late.

What not to put in a carpet cleaner

Anything that foams heavily. Dish soap, laundry detergent, shampoo. Excess foam fills the recovery tank, can reach the motor, and leaves residue in the carpet that attracts dirt for months afterward. This is the single most common way people damage these machines.

Bleach or anything harsh, which can damage the carpet fiber and the machine's seals.

If you want a lower-cost route, look for a third-party extractor solution rated as low-foaming for the type of machine you have, and follow the dosage. More soap is never better — it's the cause of the dingy-carpet problem, not the fix.

And whatever you use, an enzyme formula is the right call for pet messes specifically.

Dad’s Take: Never put dish soap in one of these. The foam is what kills the machine and leaves your carpet dirtier than it started.