Vendor 1 says it will cost you $50,000 and it will take 4 months, vendor 2 says it will cost you $100,000 and it will take 2 months, vendor 3 says it will cost you $60,000 and it will take 3 months. The average bid is $70,000, which what you put when estimating the cost of this task in your project budget. Vendor bid analysis can also be used to estimate the length of the task, by averaging all the durations submitted by the vendors in their bids. In the above example, the average length of the task is 3 months.
These days they both recommend every 5,000 miles and change the filter every time. And some people now say oil will last 10,000 miles, and we would protect the environment by not changing it as often. A 125cc bike engine works harder than a car. So I'd say changing it every 3000 miles might be justifiable.
Should you change oil as often as every 3,000 miles then? Unless you want to see your mechanic every two months, a 3,000-mile oil change interval is another extreme. If you check your oil 3,000 miles after your last oil change, chances are it will still be pretty clean. Unless you race your car daily, even mineral oil can last longer than 3,000 miles. Most car manufacturers recommend 3,750 to 10,000-mile oil change intervals.