How often must an emergency generator's oil be changed under the EPA rule?

Every 500 hours of operation or within 1 year + 30 days of the previous change, whichever comes first, unless an oil analysis program is used (40 CFR part 63 subpart ZZZZ, Tables 2c and 2d; 63.6625(i) and (j)).

Does this apply to the generator in our office building?

Not if it is an existing commercial emergency engine at an area source that is not run for the purpose in 63.6640(f)(4)(ii) (63.6585(f)). Check your engine's construction date, location and use.

What about engines installed after June 12, 2006?

At an area source, a new or reconstructed engine meets subpart ZZZZ by meeting 40 CFR part 60 subpart IIII or JJJJ (63.6590(c)). This page does not cover those rules.

What records do we need?

Records of the maintenance done and of the hours run from the non-resettable hour meter, showing emergency and non-emergency hours, kept for 5 years (63.6655(e) and (f), 63.6660).

US · Expiry & renewal tracking

Keep every emergency generator engine's maintenance on schedule

For an existing emergency stationary engine under EPA's RICE rule, the owner or operator must change the oil and filter and inspect hoses and belts every 500 hours of operation or within 1 year + 30 days, whichever is first (40 CFR part 63 subpart ZZZZ, Tables 2c and 2d). Maintenance and hour records are kept 5 years.

EPA's rule for stationary reciprocating internal combustion engines (RICE), 40 CFR part 63 subpart ZZZZ, applies to owners and operators of stationary RICE at major and area sources of hazardous air pollutants (HAP) (40 CFR 63.6585). An area source is any source that is not a major source (63.6585(c)). This page covers existing emergency engines: at an area source, an engine is existing if its construction or reconstruction started before June 12, 2006; at a major source, the same date applies to engines of 500 brake HP or less (63.6590(a)(1)). New or reconstructed engines at area sources meet the rule by meeting 40 CFR part 60 subpart IIII (compression ignition) or JJJJ (spark ignition) instead (63.6590(c)).

For an existing emergency compression ignition (diesel) engine, the oil and filter must be changed every 500 hours of operation or within 1 year + 30 days of the previous change, whichever comes first. The air cleaner must be inspected every 1,000 hours or within 1 year + 30 days, and all hoses and belts every 500 hours or within 1 year + 30 days, replacing them as necessary. For an emergency spark ignition engine, the spark plugs are inspected every 1,000 hours or within 1 year + 30 days instead of the air cleaner (Table 2c, items 1 and 6; Table 2d, items 4 and 5).

The engine must be operated and maintained according to the manufacturer's emission-related written instructions, or under the owner's own maintenance plan (63.6625(e)). An existing emergency engine must have a non-resettable hour meter (63.6625(f)). Records of the maintenance and of the hours of operation, split into emergency and non-emergency hours, must be kept (63.6655(e) and (f)) for 5 years (63.6660).

Start free

At a glance

Rule	40 CFR part 63 subpart ZZZZ, Tables 2c and 2d (EPA)
Oil and filter	Every 500 hours or within 1 year + 30 days, whichever comes first
Hoses and belts	Inspect every 500 hours or within 1 year + 30 days; replace as necessary
Air cleaner (diesel)	Inspect every 1,000 hours or within 1 year + 30 days; replace as necessary
Spark plugs (gas engines)	Inspect every 1,000 hours or within 1 year + 30 days; replace as necessary
Hour meter	Non-resettable, required
Records	Maintenance and hours of operation, kept 5 years

Not covered by the rule: existing residential, commercial and institutional emergency engines at area sources that are not run for the purpose in 63.6640(f)(4)(ii), such as office buildings, hotels, stores, medical centers, schools and apartment buildings (63.6585(f) and 63.6675). Existing emergency engines over 500 brake HP at a major source also have no requirements under the subpart (63.6590(b)(3)(iii)).

Who is responsible?

The owner or operator of the stationary engine (40 CFR 63.6585).

Hours limits and the oil analysis option

There is no time limit on use in emergencies. Maintenance checks and readiness testing are limited to 100 hours per calendar year (more with an approved petition, or where federal, state or local standards require it), and up to 50 hours of non-emergency operation count toward those 100 hours. An engine run outside these rules is no longer treated as an emergency engine (63.6640(f)). Instead of changing the oil on the fixed schedule, an owner may use an oil analysis program at the same frequency; the oil and filter must then be changed within 2 business days if a condemning limit is exceeded (63.6625(i) and (j)). If an engine is running during an emergency and cannot be shut down, the work can wait until the emergency is over, and the missed schedule must be reported (Table 2c, footnote 1; Table 2d, footnote 2).

Tracking it with ExpirySuite

Add each emergency generator engine and record the date its next oil and filter change and inspections are due: no later than 1 year and 30 days after the last one.
If the hour meter shows the engine will reach 500 hours of operation sooner, use that earlier date.
Reminders arrive 60, 30, 14, 7 and 1 day before the due date and on the due date itself.
Assign a responsible person (for example your facility or maintenance manager) so the right person gets the reminder.
If a date passes, managers get overdue reminders 3, 7 and 14 days later.
Ask the service contractor to upload the maintenance record through a secure upload link, valid for 14 days; no account is needed.

Frequently asked questions

How often must an emergency generator's oil be changed under the EPA rule?: Every 500 hours of operation or within 1 year + 30 days of the previous change, whichever comes first, unless an oil analysis program is used (40 CFR part 63 subpart ZZZZ, Tables 2c and 2d; 63.6625(i) and (j)).
Does this apply to the generator in our office building?: Not if it is an existing commercial emergency engine at an area source that is not run for the purpose in 63.6640(f)(4)(ii) (63.6585(f)). Check your engine's construction date, location and use.
What about engines installed after June 12, 2006?: At an area source, a new or reconstructed engine meets subpart ZZZZ by meeting 40 CFR part 60 subpart IIII or JJJJ (63.6590(c)). This page does not cover those rules.
What records do we need?: Records of the maintenance done and of the hours run from the non-resettable hour meter, showing emergency and non-emergency hours, kept for 5 years (63.6655(e) and (f), 63.6660).

Sources

Last checked: Oct 1, 2026 · This page summarises official sources for general information and is not legal advice. Check the linked sources for current rules and fees.

Made for emergency generator engine maintenance (EPA) (US)

A ready template for emergency generator engine maintenance (EPA) (US) with sensible validity defaults, so you enter less and track more.

Reminders on time

Email alerts at 60, 30, 14, 7 and 1 day before each emergency generator engine maintenance (EPA) (US) expires, plus overdue escalation to managers.

Assign an owner

Give each emergency generator engine maintenance (EPA) (US) an owner and let employees update their own via a secure link — no login needed.