Hi everyone, today I was driving home from work and as I took my exit off the highway, the engine knocked twice as I came to a stop and again when it reved. It didnt have an issue on the highway but I was on it for a while nonstop so the engine was hot. As I drove the rest of the way home the knock went away. Is this piston slap or bad oil or just the octane knock because the temperature changed? Coming from under the hood. Thanks!