u/Conscious_Row2824

Vehicle: 2021 Renault Talisman 1.3T (EDC)

I’ve been logging various OBD-II parameters on my daily driver. Recently, I monitored a specific parameter: “Mean value of actual retard adjustment with adaptation values (°)”. This isn't an "actual knock" event; it's the ECU preemptively pulling timing to maintain a safety margin.

1. Baseline (Normal Fuel / Old Oil) Logged my commute. Retard values stayed between -0.3° and -0.7°.
2. The Variable: Oil Change (0W-20, filled 2mm above the F mark) Immediately after the oil change, the frequency and depth of timing pull spiked significantly, hitting near -2.0°. Theory: Fresh oil's higher temporary viscosity + slight overfill = increased mechanical/fluid drag.
3. The "Human Octane" Phase The log looked slightly better the next day, but that was just me subconsciously avoiding high-load zones to keep the logs clean. Once you see the numbers, you can't "un-know" them.
4. The Solution: High-Octane (Premium) Fuel I filled up with high-octane fuel to see if it could override this mechanical resistance. The Result: Literally zero. The log became a flat line at 0.0°. Even though the engine still felt slightly "heavy" from the oil resistance, the higher octane provided enough chemical margin that the ECU stopped intervening.

I aligned these four logs into a single image for a direct comparison. Has anyone else tracked this kind of immediate ECU adaptation to oil resistance vs. fuel quality? Or is 0.0° common on these small displacement turbo engines with premium fuel?

Note: English is not my first language. I hope the data speaks for itself.