question: Why do oil changes come with a length of time along with the mileage (ex. 3 months/3000 miles)?
comment: The people that drive more would go off of mileage because of increased usage of the car and running the engine more frequently People who drive their car less frequently would go off of the time duration as they would take much too long to hit 3000 miles, picture grandma who drives down the road to church, and grocery shop and that’s it
passages: Some quick oil change shops recommended intervals of or every three months, which is not necessary, according to many automobile manufacturers. This has led to a campaign by the California EPA against the 3,000 mile myth, promoting vehicle manufacturer's recommendations for oil change intervals over those of the oil change industry.
  
  The engine user can, in replacing the oil, adjust the viscosity for the ambient temperature change, thicker for summer heat and thinner for the winter cold. Lower-viscosity oils are common in newer vehicles.
   Motor oil changes are usually scheduled based on the time in service or the distance that the vehicle has traveled. These are rough indications of the real factors that control when an oil change is appropriate, which include how long the oil has been run at elevated temperatures, how many heating cycles the engine has been through, and how hard the engine has worked. The vehicle distance is intended to estimate the time at high temperature, while the time in service is supposed to correlate with the number of vehicle trips and capture the number of heating cycles. Oil does not degrade significantly just sitting in a cold engine. On the other hand, if a car is driven just for very short distances, the oil will not fully heat up, and it will accumulate contaminants such as water, due to lack of sufficient heat to boil off the water. Oil in this condition, just sitting in an engine, can cause problems.
   Time-based intervals account for the short-trip drivers who drive short distances, which build up more contaminants. Manufacturers advise to not exceed their time or distance-driven interval for a motor oil change. Many modern cars now list somewhat higher intervals for changing oil and filter, with the constraint of "severe" service requiring more frequent changes with less-than-ideal driving. This applies to short trips of under , where the oil does not get to full operating temperature long enough to burn off condensation, excess fuel, and other contamination that leads to "sludge", "varnish", "acids", or other deposits. Many manufacturers have engine computer calculations to estimate the oil's condition based on the factors which degrade it, such as RPM, temperatures, and trip length; one system adds an optical sensor for determining the clarity of the oil in the engine. These systems are commonly known as Oil Life Monitors or OLMs.
   Section::::Maintenance.
  
  The oil and the oil filter need to be periodically replaced. While there is a full industry surrounding regular oil changes and maintenance, an oil change is a fairly simple operation that most car owners can do themselves.
   When making entries in the oil record book Part I, the date, operational code, and item number are inserted in the appropriate columns and the required particulars shall be recorded in chronological order as they have been executed on board. Each operation is to be fully recorded without delay so that all the entries in the book appropriate to that operation are completed.
  
  Section::::History of regulations for treated water discharge.
   The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold temperatures in the winter before the vehicle is started up to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature. The difference in viscosities for most single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers, or VIIs, are added to the oil. These additives are used to make the oil a "multi-grade" motor oil, though it is possible to have a multi-grade oil without the use of VIIs. The idea is to cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot. This enables one type of oil to be used all year. In fact, when multi-grades were initially developed, they were frequently described as "all-season oil". The viscosity of a multi-grade oil still varies logarithmically with temperature, but the slope representing the change is lessened. This slope representing the change with temperature depends on the nature and amount of the additives to the base oil.
   Section::::Standard practices.
  
  In addition to monitoring oil contamination and wear metals, modern usage of OA includes the analysis of the additives in oils to determine if an extended drain interval may be used. Maintenance costs can be reduced using OA to determine the remaining useful life of additives in the oil. By comparing the OA results of new and used oil, a tribologist can determine when an oil must be replaced. Careful analysis might even allow the oil to be "sweetened" to its original additive levels by either adding fresh oil or replenishing additives that were depleted.
   In "State of the World 2005", Worldwatch Institute observed that oil production was in decline in 33 of the 48 largest oil-producing countries. Other countries have also passed their individual oil production peaks.
  
  The following list shows some oil-producing nations and their peak oil production years.
  
  BULLET::::- Algeria: 2006
  
  BULLET::::- Angola: 2008
  
  BULLET::::- Argentina: 2001
  
  BULLET::::- Azerbaijan: 2010
  
  BULLET::::- Australia: 2000
  
  BULLET::::- China: 2015.
  
  BULLET::::- Egypt: 1987
  
  BULLET::::- Denmark: 2004
  
  BULLET::::- France: 1988
  
  BULLET::::- Germany: 1966
  
  BULLET::::- India: 2011
  
  BULLET::::- Iran: 1974
  
  BULLET::::- Indonesia: 1991
  
  BULLET::::- Libya: 1970 (disputed)
  
  BULLET::::- Malaysia: 2004
  
  BULLET::::- Mexico: 2003
  
  BULLET::::- New Zealand: 1997
   2018 Ford F-150 Example: According to the Scheduled Maintenance Guide of a 2018 Ford F-150 with "Lifetime Fluid" could have three different fluid service intervals depending upon how the vehicle is driven:
  
  1. Normal Driving
  
  BULLET::::- Normal commuting with highway driving
  
  BULLET::::- No, or moderate, load or towing,
  
  BULLET::::- Flat to moderately hilly roads
  
  BULLET::::- No extended idling
  
  Replace automatic transmission fluid every 150,000 mi (240,000 km)
  
  2. Severe Driving
  
  BULLET::::- Moderate to heavy load or towing
  
  BULLET::::- Mountainous or off-road conditions
  
  BULLET::::- Extended idling
  
  BULLET::::- Extended hot or cold operation
  
  Replace automatic transmission fluid every 30,000 mi (48,000 km)
  
  3. Extreme Driving
   All of this leads up to that actual pressing of the oilseed, which is followed by more procedures that involve processing the oil. Clarification removes small contaminants and impurities in the oil by letting the oil sit for a period, which allows the particles to settle. Further clarification can be done by heating the oil or filtering it through a fine cloth. Clarification extends the shelf-life of the oil from days to months.
   Lifetime automatic transmission fluids made from higher quality base oil and an additive package are more chemically stabile, less reactive, and do not experience oxidation as easily as lower quality fluids made from lower quality base oil and an additive package. Therefore, higher quality transmission fluids can last a long time in normal driving conditions (Typically 100,000 miles (160,000 km) or more).
  
  The definition of 'Lifetime Fluid" differs from transmission manufacturer to transmission manufacturer. Always consult the vehicle maintenance guide for the proper service interval for the fluid in your transmission and your driving conditions.
   The global adaptation on OBDII variants occurs during driving; on non OBDII variants the global adaptation occurs 15 minutes after engine shut down. When the engine is inside a defined load and RPM range (60 – 120 kPa and 2000 – 3000 RPM) no pointed adaptation will occur all points in the fuel matrix will be changed instead by a multiplication factor. Global adaptation can change the points in the main fuel matrix by ±25% (Tech2 shows ±100%). Adaptation occurs every fifth minute and takes 30 seconds to finish, the criteria for the adaptation are: Lambda correction is activated and the coolant temperature is above 64℃ (147F). During the adaptation the ventilation valve on the carbon canister is held close.
   Lifetime automatic transmission fluids made from higher quality base oil and an additive package are more chemically stable, less reactive, and do not experience oxidation as easily as lower quality fluids made from lower quality base oil and an additive package. Therefore, higher quality transmission fluids can last a long time in normal driving conditions (Typically 100,000 miles (160,000 km) or more).
  
  The definition of 'Lifetime Fluid" differs from transmission manufacturer to transmission manufacturer. Always consult the vehicle maintenance guide for the proper service interval for the fluid in your transmission and your driving conditions. 
   Variations in the calibration curve can lead to very different resulting calendar year ranges for samples with different radiocarbon ages. The graph to the right shows the part of the INTCAL13 calibration curve from 1000 BP to 1400 BP, a range in which there are significant departures from a linear relationship between radiocarbon age and calendar age. In places where the calibration curve is steep, and does not change direction, as in example t in blue on the graph to the right, the resulting calendar year range is quite narrow. Where the curve varies significantly both up and down, a single radiocarbon date range may produce two or more separate calendar year ranges. Example t, in red on the graph, shows this situation: a radiocarbon age range of about 1260 BP to 1280 BP converts to three separate ranges between about 1190 BP and 1260 BP. A third possibility is that the curve is flat for some range of calendar dates; in this case, illustrated by t, in green on the graph, a range of about 30 radiocarbon years, from 1180 BP to 1210 BP, results in a calendar year range of about a century, from 1080 BP to 1180 BP.
   The 3,000 mile myth refers to a common belief, particularly in the United States, that all motor vehicles should have their motor oil changed at least every to maintain their car engine. Efforts are under way to convince the public that this is not necessary and that people should follow the advice given in their owner's manual rather than the advice of oil-change businesses. With modern synthetic oils and new tests such as BMW's LL ("long life") oil specifications, most current cars can go over before needing an oil change. Even most modern conventional oils (also called mineral oils) can take a car engine at least before needing an oil change.
   Analytical techniques performed on oil samples can be classified in two categories: used oil analysis and wear particle analysis. Used oil analysis determines the condition of the lubricant itself, determines the quality of the lubricant, and checks its suitability for continued use. Wear particle analysis determines the mechanical condition of machine components that are lubricated. Through wear particle analysis, you can identify the composition of the solid material present and evaluate particle type, size, concentration, distribution, and morphology.
   In June 2011, Jiffy Lube introduced a new program called Oil Change Schedule (OCS). The new program allows Jiffy Lube customers to choose how often they have their oil changed based on a number of variables including vehicle manufacturer recommendations, driving habits, and road conditions. The OCS program moves away from the old model of changing oil every 3,000 miles and provides a schedule that is unique for each driver.
  
  Section::::Controversy.
   The symptoms of diesel bugs are easy to find. Important things to check over and look out for are:
  
  BULLET::::- Blocked Filters
  
  BULLET::::- Fuel System Failure
  
  BULLET::::- Worn Fuel Injectors
  
  BULLET::::- Corroded Tanks
  
  BULLET::::- Engine Failure
  
  Microbial contamination is significantly accelerated when higher biodiesel content occurs along with lower sulphur content.
  
  Section::::Water in oil.
   Export Land Model
  
  The Export Land Model, or Export-Land Model, refers to work done by Dallas geologist Jeffrey Brown, building on the work of others, and discussed widely on The Oil Drum. It models the decline in oil exports that result when an exporting nation experiences both a peak in oil production and an increase in domestic oil consumption. In such cases, exports decline at a far faster rate than the decline in oil production alone.
   Climate monitoring products generated from CLIMAT messages e.g. are deviations of monthly air temperature compared to the 1961-1990 reference period.
  
  Section::::Amelioration of messages.
   Lifetime automatic transmission fluids made from higher quality base oil and an additive package are more chemically stable, less reactive, and do not experience oxidation as easily as lower quality fluids made from lower quality base oil and an additive package. Therefore, higher quality transmission fluids can last a long time in normal driving conditions (Typically 100,000 miles (160,000 km) or more).
  
  The definition of 'Lifetime Fluid" differs from transmission manufacturer to transmission manufacturer. Always consult the vehicle maintenance guide for the proper service interval for the fluid in your transmission and your driving conditions. 
   Lubrication can also be done with an oil, which has advantage of higher maximum load, but needs some way to keep oil in bearing, as it normally tends to run out of it. For oil lubrication it is recommended that for applications where oil does not become warmer than , oil should be replaced once a year, while for applications where oil does not become warmer than , oil should be replaced 4 times per year. For car engines, oil becomes but the engine has an oil filter to maintain oil quality; therefore, the oil is usually changed less frequently than the oil in bearings.
   Under "Severe" driving conditions, it is recommended to refresh (change) the oil and filter of the automatic transmission every 62,000 miles (100,000 km). 
  
  3. Eight Years Old
  
  BULLET::::- ZF recommends a transmission oil change after eight years at the latest.
  
  Section::::Chrysler "Lifetime" ATF.:Example Maintenance Schedules.:6-Speed Example.
  
  A 2018 RAM 1500 with "Lifetime Fluid" and a 6-speed automatic transmission could have two different fluid service intervals depending upon how the vehicle is driven:
  
  1. Normal Driving
  
  BULLET::::- Carry passengers and cargo within recommended limits on the Tire and Loading Information label
   BULLET::::- 1942: January, February, March, April, May, June, July, August, September, October, November, December
  
  BULLET::::- 1943: January, February, March, April, May, June, July, August, September, October, November, December
  
  BULLET::::- 1944: January, February, March, April, May, June, (D-Day), July, August, September, October, November, December
  
  BULLET::::- January 1945, February 1945, March 1945, April 1945
  
  BULLET::::- 1942: January, February, March, April, May, June, July, August, September, October, November, December
  
  BULLET::::- 1943: January, February, March, April, May, June, July, August, September, October, November, December
  
  BULLET::::- 1944: January, February, March, April, May, June, July, August, September, October, November, December
   Generally, hydraulic tappets are more sensitive to engine oil quality and frequency of oil changes, as carbon sludge and residues may easily lock up the tappets or block oil channels, making the clearance setting ineffective. This has negative impact, especially on the engine camshaft and valves due to excessive wear if the clearance setting is not working correctly. As mentioned, one may avoid this by using the manufacturer-recommended grade of engine oil, and by not exceeding the prescribed oil change interval.
  