Three model needs
OasisMist 450S vs 600S: tank, routine and model-label differences
The OasisMist 450S and 600S share a connected warm/cool humidification plan, but the larger tank on the 600S does not come with a larger published room-area claim. Compare the reservoir and refill interval you can reasonably manage, then read the exact page and manual identity carefully—particularly for the 600S, whose current listing and linked manual disagree on a model-code suffix and package quantities.
Start with the documented differences
Levoit lists the 450S at 4.5 liters (1.19 gallons) and up to 45 hours on low mist. Its linked U.S. manual names model LUH-O451S-WUS, and the current product record identifies SKU HEAPHULVSUS0049. The 600S listing names a 6-liter tank and up to 60 hours on low; its current default SKU is HEAPHULVSUS0084Y. Both are rated for the same 215–430-square-foot effective range. The 600S’s greater reservoir is useful if fewer refills matter, but it is not evidence that it will cover a wider space or raise the humidity in a given room faster.
The capacity and runtime figures are maker claims, not measured tests. Levoit warns that temperature and humidity change runtime. Both manuals list 300 mL/h maximum cool output and 550 mL/h maximum warm output, three mist settings and three warm settings. Both have dual rotating nozzles, an on-device humidity display, app-linked control, an aroma-pad route and a top cover for filling. Neither is a simple appliance if you prefer to avoid account setup or the extra cleaning around a heater.
Both models have more than one humidity routine
The linked 450S manual says Auto mode responds to sensor readings, defaults to a 60% target and lets the user choose a target in VeSync. Sleep mode is separate: it selects low output, darkens the display and operates with cool mist only. The linked 600S manual describes the same two plans. A schedule is not a humidity-control setting; it says when a unit runs, while Auto responds to the sensor. If you want an app-selected target, connect the appliance and choose Auto. If you mainly want the display dark and low cool output, use Sleep. The sensor is near the aroma-box side, so placement and nozzle direction matter to its readings.
Both manuals describe phone control, humidity monitoring, timers, schedules and voice-assistant compatibility through VeSync. They do not list an included physical remote. A buyer who requires a handset should not interpret “remote control” on an app feature list as proof of a separate controller in the box.
The routine is the same even when the tank is not
Top-fill means you can add water without inverting the tank, but the manual still has you lift it from its base for filling and cleaning. Both models ask for daily water changes and tank/base cleaning every three days, with cleaning and drying before storage of a week or longer. Neither permits dishwasher cleaning, detergent or immersing the base. Levoit recommends purified or distilled water; tap minerals can leave residue. On either unit, essential oils belong only on the aroma pad—not in the tank or base—and the aroma is described as light.
The exact accessory counts differ by model and source. The current 450S page and its linked manual agree on three aroma pads, three absorption pads and two water-filter sponges, with one of each preinstalled. The 600S page lists two aroma pads, two absorption pads and one sponge; its page-linked PDF lists three of each pad and two sponges. Confirm the package and preserve its label if you need replacements. An absorption pad or water sponge does not eliminate regular tank cleaning.
Resolve the 600S label before relying on its suffix
The current 600S U.S. page links a download labeled LUH-O601S-KUS, while the linked PDF’s cover and specification table say LUH-O601S-WUS. Its current page and default variant consistently identify the product as an OasisMist 600S and SKU HEAPHULVSUS0084Y, but the exact suffix-to-SKU bridge is not settled here. The reviewed image is the official 600S gallery image; it depicts the dark cabinet, but the current page does not map that image to a separately selectable finish. If service, replacement part fit or finish-specific identity is essential, compare the physical label with Levoit support’s current model documentation before purchase.
Which one should you shortlist?
Choose the OasisMist 450S if 4.5 liters is enough, the current package list matters and you prefer the direct LUH-O451S-WUS manual match. Choose the OasisMist 600S if you need the larger six-liter reservoir and accept the 600S manual/package documentation caveats. Both carry the same area claim and care burden. If warm mist is optional, the connected Classic 300S avoids the heater and has a smaller tank. The LV600S is another large connected hybrid to compare, but has a different fill and target-control implementation. These are documentation-based assessments, not comparative lab or ownership tests; follow the exact unit’s manual for placement, water, cleaning and hot-mist safety.