LW16783-18 – Lycoming Engines OEM Oil Dipstick
Available now through the AirParts Aero marketplace.
Overview Section
The Lycoming LW16783-18 is a genuine OEM Oil Level Gauge (Dipstick) assembly designed for a variety of Lycoming four- and six-cylinder engines. As a critical engine monitoring component, this dipstick provides the pilot and maintenance crew with an accurate manual reading of the engine’s oil quantity, ensuring the powerplant operates within safe lubrication limits.
This specific dash-number (-18) refers to the calibrated length and the specific tube configuration it is designed to seat in. The unit features a high-visibility, heat-resistant handle—typically in Lycoming's signature yellow—and a precision-marked metal blade. The assembly includes the sealing gasket or O-ring required to prevent oil "burping" or crankcase pressure leaks during high-power operations.
Key Features Section
Genuine Lycoming OEM Quality: Manufactured to the exact tolerances of Lycoming Engines, ensuring the calibration marks accurately reflect the sump's oil volume.
Vibration-Proof Sealing: Features a threaded or cam-lock design (depending on the housing) that maintains a tight seal, preventing oil mist from escaping the crankcase and contaminating the engine bay.
High-Contrast Markings: The metal blade is etched with clear, easy-to-read "Full" and "Low" markings, calibrated in quarts to allow for precise oil management.
Heat-Resistant Grip: The ergonomic handle is constructed from specialized polymers designed to withstand the high temperatures of the engine compartment without becoming brittle or melting.
Corrosion-Resistant Blade: The dipstick blade is treated to resist the acidic by-products found in used aviation engine oil, preventing rust and scale buildup.
Standardized Replacement: A direct "drop-in" replacement for lost or damaged dipsticks on a wide range of O-320, O-360, and IO-540 series engines.
Technical Specifications Section
| Specification | Detail |
| Part Number | LW16783-18 |
| Manufacturer | Lycoming Engines |
| Application | Piston Engine Oil System |
| Material (Handle) | High-Temp Composite / Polymer |
| Material (Blade) | Stainless Steel or Plated Spring Steel |
| Overall Length | Calibrated for specific tube/sump depth (Verify with IPC) |
| Seal Type | Integrated Gasket / O-ring |
| Finish | Yellow (Handle) / Metallic (Blade) |
Aircraft Compatibility Section
The LW16783-18 is a ubiquitous part found across the Lycoming-powered fleet in the AirParts Aero inventory:
Cessna Series: Widely used on Cessna 172 (L/M/N/P models) and Cessna 182 variants equipped with Lycoming powerplants.
Piper Aircraft: Found on the Piper PA-28 Cherokee/Archer and PA-44 Seminole.
Beechcraft: Compatible with certain Beechcraft Musketeer and Sundowner configurations.
Grumman/Tiger: Standard equipment for the AA-5 series airframes.
Technical Applications & Safety
The dipstick is more than just a measurement tool; it is a vital part of the Crankcase Pressure System. A loose or incorrectly seated dipstick can cause a significant loss of oil through "blow-by," especially during the high-pressure environment of takeoff and climb.
Safety Warning: Always verify the part number against your engine’s Illustrated Parts Catalog (IPC). Using a dipstick with an incorrect dash number can lead to false "Full" readings when the oil level is dangerously low, or "Low" readings that lead to over-servicing and subsequent high oil temperatures.
The engineering value of the LW16783-18 lies in its Calibration Linearity and Thermal Seal Expansion. Lycoming dipsticks are calibrated based on the specific "Angle of Install" relative to the engine's sump at a standard "level flight" attitude. The -18 designation ensures that the "Full" mark accounts for the volume of oil held in the oil cooler and lines, providing a "static" reading that translates to "operational" safety.
[Image showing the etched markings on an aviation dipstick blade]
Furthermore, the seal at the top of the LW16783-18 is designed to expand slightly as the engine reaches operating temperature. This creates a positive seal that assists the Crankcase Breather system in managing internal pressure. If the seal fails or the dipstick is replaced with a non-OEM part, it can disrupt the pressure balance, leading to oil leaks at the front crankshaft seal. Choosing a genuine Lycoming part through AirParts Aero preserves the engine’s factory pressure specifications and measurement accuracy.
Installation & Maintenance Addendum
Gasket Inspection: Regularly inspect the gasket or O-ring for cracks or flattening. A worn seal is the primary cause of oil streaks on the engine cowling.
Cleaning: Wipe the dipstick with a lint-free cloth before and after every reading to prevent contaminants from entering the oil system.
Seating: Ensure the handle is turned until fully seated and locked. A "finger-tight" fit is usually required to engage the pressure seal.