Honda GX390 oil capacity and spark plug lookup
Reviewed 5 primary sourcesSee sources
Look up engine oil, spark plug or the covered reduction-case oil by GX390 engine serial number. The reviewed manuals list 1.1 L (1.2 US qt) for engine oil. That is separate from the reduction case’s oil; match the serial and compartment before using a figure.
Look up your GX390
Maintenance specs
| Honda | GX390 (reviewed serial ranges) |
|---|---|
| Engine oil capacity[2]PTO shaft type S; check the dipstick level instead of pouring a fixed amount. | 1.1 L (1.2 US qt) |
| Oil grade[2]General-use recommendation; use the temperature chart in the matched manual for other viscosities. | SAE 10W-30, API SJ or later |
| Spark plug[2] | NGK BPR6ES or DENSO W20EPR-U |
| Spark plug gap[2] | 0.7–0.8 mm (0.028–0.031 in) |
| 1/2 reduction case oil capacity[2]Only the 1/2 reduction case with centrifugal clutch described in these manuals. Separate from engine oil. | 0.30 L (0.32 US qt) |
| Displacement[2] | 389 cm³ (23.7 cu in) |
| Fuel tank capacity[2]PTO shaft type S with the tank in the reviewed specifications; the powered machine may have a different tank. | 6.1 L (1.61 US gal) |
Equipment: GX390 gasoline, horizontal-shaft engine; reviewed serial ranges only.
Oil grade
- Honda recommends four-stroke SAE 10W-30 oil meeting API SJ or later for general use. Other viscosities depend on the manual’s ambient-temperature chart.[2]
- The covered 1/2 reduction case with centrifugal clutch uses the same recommended oil grade as the engine, in a separate compartment.[4]
Fuel
- For these gasoline manuals, US pump octane 86 or higher; no more than 10% ethanol or 5% methanol. This lookup does not cover propane models.[2]
Which engines this covers
| Serial prefix | Inclusive range | Honda manual |
|---|---|---|
| GCAA | 2042139–9999999[1] | 37Z5F602[2] |
| GCAET | 1000001–9999999[1] | 37Z5F602[2] |
| GCAKT | 1000001–1372503[1] | 37Z5F602[2] |
| GCAKT | 1372504–9999999[1] | 37Z5K611[4] |
| GCANK | 1000001–1530148[1] | 37Z5F602[2] |
| GCANK | 1530149–1626671[1] | 37Z5F603[3] |
| GCANK | 1626672–9999999[1] | 37Z5F611[5] |
- Honda’s General Applications finder maps the seven inclusive serial bands above to four manuals. A similar prefix or neighboring serial is not sufficient; an unlisted range returns no specification result.[1]
- Use the engine serial stamped on the engine, not the pressure washer, mower or other powered machine’s serial. Also read the equipment maker’s manual for application-specific instructions.[5]
Not stated in these sources
- GXV390 vertical-shaft, propane and GX390 serial ranges assigned to other manuals
- Air-filter and carburetor part numbers
- Other reduction-case types or a machine-specific oil-fill amount
- A manufacture date inferred from the serial number
Sources
Facts on this page are restated from the documents below and linked to the publisher. Check the document for your exact model before relying on a value.
- GX390 owner manual finderAmerican Honda Motor Co. · General Applications: prefix, inclusive serial range and linked manual · retrieved
- GX240 / GX270 / GX340 / GX390 owner manualHonda Motor Co. · 37Z5F602 · English printed pp. 7–10: safety, oil and reduction case; p. 12: plug and gap; p. 16: serial location; pp. 18–19: GX390 PTO type S specifications and quick reference · retrieved
- GX240 / GX270 / GX340 / GX390 owner manualHonda Motor Co. · 37Z5F603 · English printed pp. 7–10: safety, oil and reduction case; p. 12: plug and gap; p. 16: serial location; pp. 18–19: GX390 PTO type S specifications and quick reference · retrieved
- GX240 / GX270 / GX340 / GX390 owner manualHonda Motor Co. · 37Z5K611 · English printed pp. 7–10: safety, oil and reduction case; p. 12: plug and gap; p. 16: serial location; pp. 18–19: GX390 PTO type S specifications and quick reference · retrieved
- GX240 / GX270 / GX340 / GX390 owner manualHonda Motor Co. · 37Z5F611 · English printed pp. 7–10: safety, oil and reduction case; p. 12: plug and gap; p. 16: serial location; pp. 18–19: GX390 PTO type S specifications and quick reference · retrieved
Primary publishers: American Honda Motor Co., Honda Motor Co.. Spotted an error? Email the address in the footer with the model and the document you are using.