Oil changes are the most routine maintenance task in general aviation. Most owners do several a year. And most owners, if they're honest, find the logging part a little tedious — especially when the format changes every time depending on who recorded it last.
This post covers what a good oil change log entry should include, how tach time and calendar intervals interact, and how to use master items in Aircraft Logs to make each entry take about thirty seconds.
What Belongs in an Oil Change Entry
A complete oil change log entry should capture:
- Date — the calendar date of the service
- Tach time — current tachometer reading at time of change
- Oil drained — quantity and type of oil removed
- Oil added — quantity, brand, and specification (e.g., Phillips 20W-50, AeroShell W100)
- Filter — part number of the new filter installed
- Inspector — A&P certificate number if a mechanic performed or supervised the work
- Next due — the tach time or calendar date when the next change is due
That last point — next due — is one owners most often skip. Skipping it means you have to do the math again every time you need to know when service is due. Log it once, and every future lookup is instant.
Tach Time vs. Calendar Time: Which One Governs?
The answer depends on your engine manufacturer's recommendation and how much you fly.
Most piston aircraft manufacturers recommend oil changes every 25–50 hours of operation, or every four to six months — whichever comes first. That "whichever comes first" is the part that trips people up.
A lightly flown aircraft sitting on the ramp for six months needs an oil change even if it only has 8 hours on the engine since the last service. Oil oxidizes, moisture accumulates, and acids build up regardless of flight hours. Calendar time is a real interval, not a technicality.
The cleanest way to track this is to log both at every change:
- Next due by tach: current tach + interval hours
- Next due by calendar: today's date + interval months
Whichever arrives first wins. Aircraft Logs tracks both and shows you your status at a glance.
Using Master Items to Speed Up Entry
In Aircraft Logs, a master item is a pre-configured maintenance template. You create it once with all the standard fields filled in — oil type, filter part number, interval — and reuse it every time that service comes around.
For an oil change, a master item saves you from re-entering the same information every three months. You open it, update the date and tach time, confirm the filter part number, and save. The entry is done.
To set one up:
- Navigate to Maintenance → Master Items in Aircraft Logs
- Create a new item named something like "Oil Change — 25hr / 4mo"
- Set the default work description, oil specification, and filter part number
- Set the interval triggers for both tach hours and calendar months
- Save it
The next time you do an oil change, open that master item, fill in the tach reading and date, and Aircraft Logs handles the rest — calculating the next due date and updating your maintenance status automatically.
A Note on Owner-Performed Maintenance
Under 14 CFR 43 Appendix A, oil and filter changes are listed as preventive maintenance that a certificated pilot can perform on an aircraft they own and operate. If you do your own oil changes, your log entry should note your pilot certificate number and that the work was performed as preventive maintenance under Part 43.
If an A&P performs or supervises the work, their certificate number and signature belong in the entry.
Either way, a clear, consistent entry protects you and makes your records easy to verify at the next annual.
The oil change is routine. The logging doesn't have to be a chore. With a master item set up once, you'll have a complete, consistent record with almost no effort — and the peace of mind of knowing exactly when the next one is due.