Should You Add Oil To The Fuel For Evinrude E-TEC Engines To Lubricate The Injectors?
Good question — I know why you’re asking. Some owners of direct-injected two-strokes (including Evinrude E-TECs) wonder if adding oil to the fuel might help lubricate the injectors or reduce wear.
The short answer from BRP/Evinrude: No, you should not add oil directly to the fuel on an Evinrude E-TEC.
Here’s why according to BRP/Evinrude:
-
E-TEC injectors are not fuel-lubricated.
Unlike older outboards that relied on oil in the fuel stream, E-TECs use a stratified direct injection system. Fuel is injected directly into the combustion chamber, and lubrication is handled by the engine’s dedicated oiling system, not by mixing in the tank. -
The system is engineered for precise ratios.
The E-TEC computer (EMM) meters oil injection at extremely controlled rates, varying with RPM and load. Adding oil to the fuel bypasses that calibration, can foul plugs, clog injectors, or alter spray pattern. -
Injector wear isn’t oil-related.
The injectors are electromagnetic/mechanical devices with internal fuel passages. Their biggest enemies are contamination (silt, sand, varnish), not lack of lubrication. That’s why fuel quality and filtration are so critical. -
BRP/Evinrude never recommended adding oil.
In fact, their manuals caution against altering fuel/oil ratios. The system is designed to run clean on straight, high-quality gasoline with the oil provided only through the E-TEC oiling system. - If you’re worried about injector life, the real preventative measures are:
-
Use clean, fresh fuel (top-tier, ethanol-free if possible).
-
Keep the fuel system dry (no water contamination).
-
Replace filters regularly.
-
Periodically run the engine hard enough to keep it clean (E-TECs like being run, not idled forever).
-
Here’s a breakdown of what actually causes Evinrude E-TEC injectors to fail or drift out of spec over time.
E-TEC injectors are very different from port injectors or even automotive GDI injectors. They are precision metering devices with multiple internal wear points, and the biggest issues are not about lubrication.
1. Mechanical Wear & Fatigue
-
The injectors have an internal plunger and spring assembly that opens and closes at very high speed.
-
Over time, springs weaken, plungers wear, and tolerances change → leading to poor spray shape or erratic delivery.
-
This is normal aging — adding oil won’t prevent it.
2. Electrical Coil Degradation
-
The E-TEC injector coil fires at extremely high frequencies.
-
Heat cycles and vibration can cause insulation breakdown or resistance drift.
-
This shows up as injectors that fail the “coil check” in diagnostic testing.
3. Contamination (Most Common)
-
Silt, sand, varnish, corrosion inside the injector restrict flow or alter spray.
-
Water contamination causes rust and deposits.
-
Ethanol fuels that absorb water can accelerate corrosion.
-
This is why BRP and injector specialists stress filtration and fuel quality.
4. Seal & O-Ring Issues
-
The sealing surfaces can harden, shrink, or crack with age.
-
Leads to air/fuel leaks, misfires, or loss of pressure.
What Does Help Longevity
-
High-quality fuel (non-ethanol preferred).
-
Regular filter changes (don’t let junk into the rail).
-
Periodic professional cleaning & flow testing — restores spray, clears varnish.
-
Running the motor — E-TECs like to be worked, not idled endlessly.
-
Proper oil (BRP XD100 or equivalent) through the designed injection system.
The Bottom Line
-
Preventative cleaning: great at catching injectors before problems worsen.
-
Corrective cleaning: sometimes buys time, but often the injector is already worn.
Think of it like brakes: cleaning prevents squeaks and sticking, but if the pads are worn down, you’re not restoring them — you’re just trying to salvage what’s left.
All that said; I personally would run 400:1 in the fuel but that’s me.