Originally Posted By: callbay
It usually seems like new oil runs smoother even if it's the same brand and type as the old oil. Especially if the oil was overdue for a change (not my own vehicles overdue of course!)
Its true, as much as some BITOGers will argue that oil with 5,000 miles on it protects just as good as new oil and can keep protecting for another 5k, the reality is that even after 500 miles, the USED oil is now performing at 90% efficiency.
Its not only a placebo effect.
When my sister had her S2000 and i would service it without her knowing, within 15 mins of leaving the house, she'd call and be like "did you just change the oil, cause its revving so much smoother"
Goes to show that even though she had no idea that i just changed the oil, my 18 year old sis could tell a difference in performance from the old oil with 4k on it vs fresh juice.