A little off topic:

Why is it that everytime we have our oil change, our engine response especially during the acceleration in 1st gear is excellent. After sometime, it becomes sluggish and at times you could feel the excellent acceleration as well but not consistent as it was when the oil is newly change. Based from what I have read, oil doesn't degrade as long as we observe proper OCI and the main reason why we change our engine oil is to avoid sludge formation. Based on that premise alone, what could be the reason popular known as "kulang sa hatak"? Is it the wrong type of oil that we use? of course, there are many other factors involved but let us just concentrate on oil in relation to an engine's performance. Your insights is much appreciated.