http://www.oilspecifications.org/art..._explained.php
Drain Intervals
Long drain compatible vehicles are also equipped with a WIV service computer, which may decide to order an oil change sooner if the operating conditions are less than optimal (e.g. too many cold starts, too short trips, etc.).
從這段文字看來,太常短途行駛,太常冷啟動,即使是 long life 機油仍需要由電腦判斷是當的縮短換油里程.
http://bobistheoilguy.com/engine-oil-analysis/
TBN
The TBN (Total Base Number) is a lubricant’s reserve alkalinity measured in milligrams of potassium hydroxide, or calcium sulfonate per gram of oil. In more simple terms it is the amount of active additives remaining. This number is important because combustion byproducts tend to form acidic compounds and the TBN is the acid-neutralizing capacity of the lubricant. The TBN does not decrease linearly with the time it has been in use. Example: it could start out at a TBN of 10, drop to 5 after only 1,000 miles of use, and then stabilize around 3 for a majority of the remaining service life. A TBN of <1.0 is generally considered to indicate near depletion of additives, and is a safe point to change your oil. Once the additives are depleted then the infamous sludge that the crazy Scot from the Castrol commercials has been warning us about can begin to form. A virgin sample of the identical oil that I used here (Pennzoil Ultra 5w30) begins with a TBN of 11.7.
從這段文字來看, TBN 可以判斷還有多少添加物存在,TBN<1 以後就可能使油泥大量增加,所以建議此時換油.
但我覺得這只是從不產生油泥的角度來看, 潤滑效果此時可能也變差了,其他一堆的項目應該都要納入考量才是.
Aluminum,Chromium,Iron,Copper,Lead,Tin,Molybdenum,Nickel,Manganese,Silver,Titanium,Potassium,Boron,Silicon,Sodium,Calcium,Magnesium,Phosphorus,Zinc,Barium,SUS Viscosity @ 210°F,cSt Viscosity @ 100°C,
Flashpoint in °F,Fuel %,Antifreeze %,Water %,Insolubles %,TBN,TAN
說真的,上述真的很多,我很懷疑 WIV service computer 如何能綜合評價?