The 3500 Super Quiet Inverter puts out 3,000 W continuously and up to 3,500 W for a few seconds when a motor starts. It runs up to 11 h at 25% load on a full 2.33 gal8.8 L tank. Noise is rated at 57 dBA at 23 ft, 25% load. It takes 20 fl oz0.59 L of engine oil, and the source recommends SAE 10W-30. The spark plug is Torch F6RTC or equivalent, gap 0.027–0.031 in.
Specifications
Units: /| Power | |
|---|---|
| Running output | 3,000 W 1 |
| Starting output | 3,500 W 1 |
| Voltage | 120 V 1 |
| Inverter (clean power for electronics) | Yes 1 |
| Engine | |
| Displacement | 212 cc 1 |
| Fuel and run time | |
| Tank | 2.33 gal8.8 L 1Figure from the item 71358 manual. Harbor Freight has printed other tank sizes in other versions of the manual, so check the one for your item number. |
| Run time | 11 h 1at 25% load |
| Size and noise | |
| Noise | 57 dBA 1at 23 ft, 25% loadHarbor Freight's product page rates it at 56 dBA. |
| Outlets | |
| Outlets | 2 × 120 V 20 A (5-20R) 1 × 120 V 30 A twist-lock (L5-30R) 1 × 12 V DC two-pin outlet (8 A) |
| Other | |
| CO shutdown | CO SECURE 2 |
| Emissions certification | CARB compliant version: item 72899 2 |
Oil, spark plug and service
What to have on the bench before an oil change or tune-up.
| Oil capacity | 20 fl oz0.59 L 1 |
| Oil type | SAE 10W-30 1 |
| Spark plug | Torch F6RTC or equivalent, gap 0.027–0.031 in 1Page 20 of the same manual says to use only F7RTC. |
| Change oil every | After the first 30 hours (break-in), then per the manual's schedule 1 |
Parts
Search links for common parts. Check the part number against the label on your unit before you buy.
| Part | Find it |
|---|---|
| Air filter | Amazon · eBay |
| Spark plug | Amazon · eBay |
| Carburetor | Amazon · eBay |
| Parallel kit | Amazon · eBay |
We may earn a small commission if you buy through these links. It doesn't change what we list. More.
Model numbers
This page covers model numbers 71358, 72899, 59137. Brands often sell the same name under several numbers with small differences, so check the label on the frame.
Compare
Often compared: Champion 201318 4500-Watt RV Ready Inverter, Westinghouse iGen4500, Predator 3500 Super Quiet Inverter (item 56720), Honda EU3000iS
Questions people ask
How much oil does the Predator 3500 Super Quiet Inverter take?
20 fl oz0.59 L. Oil type: SAE 10W-30. Oil change: After the first 30 hours (break-in), then per the manual's schedule.
What spark plug does the Predator 3500 Super Quiet Inverter use?
Torch F6RTC or equivalent, gap 0.027–0.031 in, according to the source. Check the plug in your unit before you buy a replacement.
How long does the Predator 3500 Super Quiet Inverter run on a tank?
11 h. That's at 25% load, according to the source. More load means less time.
How loud is the Predator 3500 Super Quiet Inverter?
57 dBA. Measured at 23 ft, 25% load.
What's the difference between 3,000 W and 3,500 W?
3,000 W is what it can supply continuously. 3,500 W is a short burst for the moment a motor (a fridge, a pump, an AC unit) starts up.
Sources
- Harbor Freight owner's manual, item 71358 (UPC 193175546265). Owner's manual, accessed November 11, 2026.
- Harbor Freight product page, item 72899. Retailer listing, accessed November 9, 2026.
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