Electric motor data tag for oil burner (C) Daniel FriedmanElectric Motor Lubrication Schedule
How often to lubricate electric motors & what type of oil to use

  • ELECTRIC MOTOR LUBRICATION - CONTENTS: typical lubrication schedule for electric motors used on HVAC equipment.
  • POST a QUESTION or READ FAQs about how to troubleshoot electric motors such as air conditioning compressor motors, heating equipment burner or fan motors, swimming pool motors, water well pump motors

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Electric motor lubrication schedule & oiling ports:

This article explains the typical lubrication requirement for for motors found on HVAC equipment in buildings such as air conditioners, furnace or air handler blower fans, oil burner motors, well pumps, and condensate return pumps. While some motors are permanently lubricated, others require lubrication as often as annually, depending on the motor usage level.

A simple check of the motor's data tag, explained here, can give the lubrication requirements needed to keep the motor running reliably and safely.

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Electric Motor Lubrication Specifications & Schedules: when, how much oil, where to oil

Becket oil burner electric motor (C) Daniel Friedman The two approaches to lubricating the moving parts of an electric motor are:

Permanently-lubricated electric motors: the motor has no oiling ports, has sealed lubricated bearings installed at the factory. Watch out: this motor should not be oiled. Doing so may damage the motor.

Duty-cycle based manually lubricated electric motors: these motors require maintenance according to how much they are in use (their duty cycle) and will have oiling ports, usually an open tube or an openable metal cap at either end of the motor.

Here are Beckett's (1989) recommended motor oiling intervals:


Air Conditioner, Heat Pump, or Heating System Electric Motor Lubrication Schedule

Duty Cycle  Explanation of electric motor duty cycle Lubrication Frequency (Years) 
Occasional Duty Electric Motors Motor runs less than 2 hours per day 5 years
Intermittent Duty Electric Motors Motor runs 2-12 hours per day 2 years
Continuous Duty Electric Motors Motor runs 12 or more hours per day Annually
Permanently-lubricated Electric Motors No oil ports, factory-sealed pre-lubricated bearings Never


At ELECTRIC MOTOR DATA TAG we explain all of the information that can be found on the electric motor data tag, including the motor's lubrication requirements.

How much oil is required when lubricating an electric motor? The answer is I can't say because the quantity varies according to the motor design.

For the oil burner motor whose data tag is illustrated at the top of this page, re-oil instructions specify that each bearing is to be lubricated with 150 drops (about one teaspoon) of SAE 20 oil.

Watch out: Lubrication should be with an oil and at frequency specified by the equipment manufacturer. If you don't have this data use the table above. Lubrication typically is with SAE 20 oil, droplets or tube-fed into the motors (usually two) oiling ports.

Watch out: Do not soak the motor in oil, do not spray the motor windings with spray oils like WD40, do not try to lubricate permanently-lubricated motors that don't have an oil port.

Watch out: lack of lubrication can cause an electric motor to overheat, go off on thermal overload (ELECTRIC MOTOR OVERLOAD RESET ), or to become noisy (ELECTRIC MOTOR NOISE DIAGNOSIS) and ultimately to fail.

Watch out: if the motor's data tag indicates that it is permanently lubricated or does not require lubrication, don't try to lubricate it - you're likely to cause damage or even an unsafe motor.

How & Where to oil an electric motor

Reader Question: where are the lubrication points for an electric motor such as the Emerson K55hxkwa-9803 ?

(July 23, 2014) Jeff Wilmsmeier said:

Can you oil a Emerson K55hxkwa-9803


Jeff I had trouble finding a manual for this fan motor online too - so I don't know the answer.

Look closely at the motor assembly. Oil ports will be obvious, often capped with a hinged cap or a hole facing up marked "OIL" on the steel body of the motor.

Or send us some sharp photos of all sides of the motor and we'll comment further.

Below we illustrate three electric motors, all happening to be found in heating furnace blower compartments.

At below left we see an electric motor that is permanently-lubricated or factory-lubricated. There are no visible oiling points. Oil points on a typical electric motor such as these furnace blower motors will be visible as a small metal cap that opens on a vertical tube that directs a few drops of proper lubricating oil onto the motor's bearing and shaft end (red arrow, below-right).

Electric motor with no lubrication ports (C) Daniel Friedman] Electric motor lubrication points (C) Daniel Friedman

Other older electric motors may also have oiling points without the vertical lubricant directing tube, just a rubber or metal cap over the oil insertion point such as shown in our photo at below left (blue arrow).

Electric motor with rubber cap over lubrication point (C) Daniel Friedman


Continue reading at ELECTRIC MOTOR NOISE DIAGNOSIS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Or see ELECTRIC MOTOR DIAGNOSTIC FAQs-2 - more questions & answers about fixing electric motors




Suggested citation for this web page

ELECTRIC MOTOR LUBRICATION at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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