Parts Washer Fluid: Paraffin, Solvent or Water? Pick It Right

A carburettor full of varnish, a gearbox casing caked in oil, a tub of seized bolts: whatever you clean, the fluid in the tank matters as much as the washer. The wrong fluid can be a fire risk, and some washers take water-based cleaners only.

Match the fluid to the washer first, then the washer to the parts. PartsForMachines lists 20 products, from parts washers and ultrasonic tanks to a vibratory tumbler, from Sealey, Draper and SIP in its parts washer range.

Paraffin, Solvent or Water-Based: What Should Go in My Parts Washer?

Use only the fluid type the washer was designed for: paraffin and white spirit go only in a tank its maker approves for solvent, and water-based cleaners suit the rest. Some electric washers, such as the 37825 floor-standing washer and the 22494, are not suitable for solvent; the 22494 is meant for water-based cleaners only.

Others, including the SM19 and SM28, circulate solvent through a sealed magnetic drive pump and have a fusible-link fire lid. If you want solvent where flammable vapour is a worry, an air-operated tank such as the SM22 runs with no electricity at all.

Ultrasonic Tank or Solvent Washer: Which Cleans Carburettors Better?

For a carburettor, an ultrasonic tank usually does the better job, because it reaches jets and passages that a brush cannot. High-frequency vibration forms tiny bubbles that collapse and scrub out the crevices.

A 9-litre ultrasonic tank such as the SCT09 has a 300 x 240 x 150mm tank, heats up to 80°C and runs cycles of up to 30 minutes. Use water, a non-volatile cleaning agent or the maker’s recommended ultrasonic fluid, never paraffin or other flammable solvent: heat and vibration raise vapour that an electrical spark could ignite. Big castings and long shafts suit a recirculating tank instead.

Brush or Nozzle, and What Keeps the Pump Alive?

A brush on the hose saves time, because you scrub while the fluid washes the dirt away; with a plain nozzle you need a separate brush. The SM222 tank with a flow-through brush pumps filtered fluid out through the brush and takes soluble cleaning agents only.

Use only fluids the maker allows, keep the fluid within the working capacity and keep the filter clean: on tanks such as the SM21, fluid is filtered before it reaches the pump. The SM21 pump also has a replaceable impeller. Need a new pump? Send us the washer’s model number.

Dirty Fluid: How Often Should I Change It and How Do I Get Rid of It?

How often depends on how dirty your parts are, so change the fluid once it stops getting them clean. A good filter makes each fill last longer, and washers such as the SM40 and 37825 have a replaceable one. The SM224 mobile tank with its own reservoir adds a level indicator and a drain tap for emptying.

Drain old fluid into a container and never tip it down a drain. Rules vary by country. In England, for example, waste oil from a business counts as hazardous waste, and it is normally collected by a registered waste carrier, with a consignment note.

What Should I Check Before I Buy?

• which fluid the washer allows: water-based only, soluble agents only, or solvent
• the internal tank size against your largest part, including depth for long shafts
• the minimum and maximum working capacity, so you know how much fluid to buy
• the power supply: a 230V socket, or compressed air (the SM22 needs 6cfm at 90psi)
• safety and servicing features: a fusible-link lid, filter, drain tap and brush

If you are unsure which washer suits your parts or your fluid, contact the PartsForMachines team by WhatsApp, telephone or email, or browse the parts washer range.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

How much fluid does my parts washer actually need?

Enough to reach the minimum working capacity, not just a splash in the bottom of the tank. The SM19 holds 40 to 50 litres, the bench-top SM21 7 to 15 litres and the extra-deep SM40D 91 to 136 litres.

What size of parts washer do I need?

Measure the largest part you clean often and compare it with the internal tank size, not the overall size. The SM21 tank measures 395 x 290mm; long shafts need a deep tank, such as the 400mm-deep SM40D.

Can I use petrol or diesel in a parts washer?

Never petrol: it gives off highly flammable vapour that a spark can easily ignite. For diesel or any other fluid, follow the washer maker’s instructions, and if they do not approve it, do not use it.

Can I use plain water in an ultrasonic cleaner?

The Draper tanks, such as the 92635, are rated for water or a non-volatile cleaning agent; for the SCT09 and other SCT tanks, Sealey recommends its own SCT25D fluid. Check first that the item suits ultrasonic cleaning.

What does the fusible link on the lid do?

It is a fire safeguard: if a fire breaks out, the fusible link lets the lid snap shut automatically, with no action from you. Tanks such as the SM19, SM22 and SM224 have one.

Should I choose an air-operated or an electric parts washer?

Choose air-operated where flammable vapour is a concern or there is no socket: the unit has no electricity, but needs about 6cfm of compressed air. Once charged, the SM224 can run for a limited time away from the air line.

What does the turbo feature on a parts tank do?

It bubbles workshop air through the fluid to agitate it, loosening grease faster than soaking alone. On the SM20 it needs an air supply as well as 230V, and the tank also works with the turbo off.

What temperature and time should I set on an ultrasonic cleaner?

It depends on the part and the fluid, so check the fluid maker’s limits. Our tanks set up to 80°C, with timers of 1 to 30 or 1 to 99 minutes depending on the model; use soft mode, where fitted, for delicate items.

Can a vibratory tumbler replace a parts washer?

For batches of small metal parts, it can handle rust removal, deburring and polishing. The SB949 has a 250mm bowl and runs wet or dry with media; it suits small parts, so large castings still need a tank.