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.
If you're nervous about going 10,000 miles or more between oil changes, then do it every six months, when you probably should also have your tires rotated (also explained in your owner's manual).GM says to change your oil at least once a year even if the service indicator warning light doesn't come on.MW says owners can go up to 15,000 miles between oil changes (with synthetic oil). The intervals vary by manufacturer and engines, so consult your owner's manual or maintenance schedule to see how often to change the oil in your vehicle and what type of oil to use. You may be surprised.