Frequently Asked Questions

What type of oil should I use in my engine?

Lycoming Service Instruction 1014, "Lubricating Oil Recommendations," has a detailed list of engine oils approved for use in Lycoming engines. The Service Instruction also has information on what lubricating oils to use at your average operating temperatures and what types of oil to use during the break-in period.

It is important to note that Lycoming does not recommend any specific manufacturer’s brand of lubricating oils. Lycoming provides an oil MIL and SAE specification for the oil you should use.  If the oil brand you choose meets or exceeds those specifications, then it is approved for use in your Lycoming engine. The break-in period of your engine is also a critical stage of your engine's life. It is important that you use the correct lubricating oil during this time to ensure a quick and proper break-in to get a long and reliable service life from your engine. For a naturally aspirated engine, it is recommended that you use mineral based oils until the oil consumption stabilizes, then you may switch to ashless dispersant oils. Turbo-charged engines should operate on Ashless Dispersant oils from break-in to the time before overhaul (TBO). Please reference SI 1014 for more details.

How many hours does my engine have until TBO?

Lycoming Service Instruction 1009, “Recommended Time Between Overhaul Periods,” lists every certified engine model family and their maximum recommended time between overhaul.  It is important that you read all of the information that applies to your engine model to determine an accurate TBO recommendation for your engine.  If you have any questions or concerns, contact Lycoming Technical Support.

All Lycoming Engines have a recommended calendar overhaul of 12 years regardless of the time on the engine. The recommended time to overhaul is important for a couple of reasons: engines that operate infrequently often have a much higher chance of corrosion forming on parts exposed to the environment, and the engine uses composite gaskets and rubber hoses that degrade over time and could affect the reliability of your engine.

What type of spark plugs can I use in my engine?

Lycoming Service Instruction 1042 lists all approved spark plugs by engine model. Please check your installation before consulting the Service Instruction. Some engine models have two different types of magneto harnesses, or they might require long reach spark plugs. Those items will impact which table within the Instruction you need to consult for the proper spark plug part numbers.

Is my Lycoming core eligible to be returned to the factory?

Yes! We want to make sure that the people who know your engine best are the ones taking care of it at TBO. Lycoming Service Letter 250, "Lycoming Engines Exchange Engine Core Policy," gives general guidelines for a core exchange engine. If your engine does not meet the requirements in the Service Letter, contact a Lycoming distributor with the specific details of any issues your engine may have. Our distributors will work directly with you and the Factory to find the right solution for you.

How do I break in my engine?

Lycoming factory engines are test run and inspected for leaks before leaving our factory. Therefore, the break in process has already been started for you. Follow these easy steps for approximately the first 25-50 hours of operation:

  1. Service your engine with the proper oil recommended in Lycoming Service Instruction 1014, "Lubricating Oil Recommendations."
    1. Naturally aspirated engines (no turbocharger) should be run on mineral based oils for break-in until oil consumption stabilizes.
    2. Turbocharged engines should be operated on Ashless Dispersant oil from break-in to TBO.
  2. Follow the oil change intervals listed in Service Bulletin 480, "Oil and Filter Change and Screen Cleaning." You should complete the first oil and filter change at 25 flight hours.
  3. Cruising should be done at 65% to 75% power until a total of 50 hours has accumulated or oil consumption has stabilized to ensure proper seating of the rings and applies to new engines.
  4. Cylinder head temperatures should be kept cool. Decrease climb angles to increase speed; the extra air will help cool your cylinders as they break in.

Avoid low power operations during the break in period. This is probably not the time for you to practice your landings. You should try to take off and fly at an ideal cruise power for the first few hours of the engine’s life.

What are field overhauled engines?

You should treat field overhauled engines or engines that have recently had a cylinder changed differently. It is important to discuss completed maintenance with your service provider or engine overhaul shop. Lycoming Service Instruction 1427 gives recommendations for test running and break in of field overhauled or field repaired engines.

Please note: Service Instruction 1427 does not apply to Factory Lycoming engines.

How do I care for my engine in cold weather?

Lycoming engines can be operated in most climates, but there are a few things to consider when operating your engine in cold environments:

  • Ensure that you use the correct oil for the ambient temperature in your environment.  Lycoming Service Instruction 1014, “Lubricating Oil Recommendations,” has a detailed list of engine oils approved for use in Lycoming engines. 
  • Most of the systems on Lycoming engines are mechanical, meaning they do not rely on electronics. Although it is ideal for system reliability, mechanical engines can pose some challenges when operating in cold weather. Lycoming Service Instruction 1505, "Cold Weather Starting," gives some recommendations on preparing your engine to fly on a cold day. The instruction recommends the engine be pre-heated to assist with starting and to prevent damage from very cold and thick oil. The Instruction also suggests that the engine is warmed up to full operating temperature before takeoff.
How often should I change my oil?

Lycoming’s Service Bulletin 480,“Oil and Filter Change and Screen Cleaning; Oil Filter/Screen Content Inspection," provides aircraft owners with Lycoming Engines' recommendations for oil changes. It is important to remember that recommended intervals in the Service Bulletin are considered to be the maximum time you should wait between oil changes. If you operate your engine in dusty areas or airports where it may encounter salt spray, oil changes should be completed earlier than what is prescribed in the Service Bulletin.

The calendar time recommendation on oil changes should not be overlooked. As mentioned in the cleaning section above, oil picks up some acidic combustion byproducts. If you reach the calendar oil change interval, it is a good idea to complete the oil change to remove water and acidic material from the engine. Clean, fresh oil is a low-cost way to keep other maintenance costs low.

What should I do if I find metal in my filter?

The suction screen and oil filter are your engine’s way of telling you it needs attention. Very light traces of metal are normal and should not be too concerning, especially during engine break-in. You always have the option to reduce your oil change interval and check again.

Service Instruction 1492, “Piston Pin Plug Wear Inspection,” provides information on what to do if you find metal in your filter. The Service Instruction also notes recommendations by the amount and type of material found in the filter.

What fuels can I use in my engine?

Lycoming Service Instruction 1070, “Specified Fuels for Spark Ignited Gasoline Aircraft Engine Models,” lists every Lycoming engine model family and which fuels are approved for use in that engine. Please note that some of the fuels listed in the Service Instruction may not be available in your geographic region. Be sure to read the document carefully so that you understand how fuels are rated and what additives may exclude you from using certain fuel choices. This is especially important if you intend to use an automotive pump gasoline.

Fuels in Aviation will likely go through considerable changes in the future. Be sure to check back for new revisions of this Service Instruction as new fuels and information become available.

How do I lean my engine?

First and foremost, follow the approved Pilot's Operating Handbook (POH) for your aircraft. Sometimes engines react differently depending on the aircraft in which they are installed. The POH has the most relevant data because your specific engine model was tested during the aircraft’s certification.

For recommendations from Lycoming Engines, Service Instruction 1094, "Fuel Mixture Leaning Procedures," gives general guidance and techniques for leaning your engine. Again, these are recommendations, and the aircraft POH is your approved source for leaning procedures. Service Instruction 1094 will provide you with greater detail on how to lean to provide the best possible service life of your engine.

What’s the difference between a Factory new, rebuilt, and overhauled engine?

Factory New – Everything in the engine or installed on the engine is brand new.  The engine has a zero time since new and zero time since major overhaul.  These engines are identical to what an OEM customer (such as Cessna or Piper) would be installing into their brand new aircraft.  New engines carry a two-year factory warranty up to the hourly overhaul period listed in Service Instruction 1009. This engine choice makes sense for the customer that likes to have the peace of mind of having everything be brand new.

Factory Rebuilt – Every part used in building the engine meets or exceeds new part specifications; or the engine is like new. It has a zero time since new and a zero time since major overhaul. Some parts may be used, but they meet the same specifications as a new part. Like new engines, this engine carries a two-year factory warranty up to the hourly overhaul period listed in Service Instruction 1009. This engine choice is for the customers who are looking to have a return on their investment by adding value to their airframe.

Overhauled – The parts used to build the engine meet or exceed service limits and specifications. The engine carries the previously accrued total time since new, but has zero time since major overhaul.   This engine also carries a one-year factory warranty up to the hourly overhaul period listed in Service Instruction 1009. An overhauled engine is best for the customer who is looking for the most cost-effective option, or for those who accrue hours very quickly and will likely run the engine through the next overhaul cycle. Some parts are no longer available new from the original equipment manufacturers, such as dual magnetos from Bendix/TCM. In these cases, those parts are overhauled by a reputable overhaul facility.

All Lycoming factory new, rebuilt and overhauled engines are built on the same production assembly line. The same skilled workers build all types of engines, new or overhauled, 4-cylinders or 8-cylinders, and naturally aspirated or turbocharged.

I lost my engine data plate, what should I do?

Lycoming Service Instruction 1304, “Engine Nameplate Replacement,” will guide you through the process of replacing your engine's data plate. You will be required to acquire a letter from your FAA representative ensuring that you indeed have the serial number engine that you are requesting. The serial number can be found stamped in the case halves.  

Send your FAA letter of approval, a letter requesting a new data plate, and a check for $125 to the address listed in Service Instruction 1304.  Your order can be processed via telephone using a credit card by contacting Lycoming Technical Support

What qualifies as a prop strike? What should I do if I had a prop strike?

Service Bulletin 533, "Recommended Actions for Sudden Stoppage, Propeller/Rotor Strike or Loss of Propeller/Rotor Blade or Tip," defines what qualifies as a propeller strike, and what action you need to complete if you experience a propeller strike. Determining whether an event is a propeller strike requires the pilot and maintenance provider to use their best judgment. Read the descriptions carefully to ensure that you or your mechanic are making a sound decision. Propeller strikes can be, but are not limited to, the following events:

  • Any incident, whether or not the engine is operating, where repair of the propeller is necessary.
  • Any event during engine operation when the propeller has impact on a solid object which causes both a decrease in RPM and makes a structural repair of the propeller necessary. This type of incident includes propeller strikes against the ground. When the propeller can continue to rotate, engine damage can occur, with possible progression to engine failure.
  • Sudden RPM drop on impact to water, tall grass, or a similar yielding medium where propeller damage does not usually occur.

If you determine that you have had a propeller strike, a full tear down inspection is recommended. Service Bulletin 533 documents the inspection procedure for prop strikes.

Please note that an FAA Airworthiness Directive that applies to actions that must be completed on Lycoming engines that have suffered a propeller strike. Be sure to review their recommendations at FAA.gov before returning the aircraft to service.