XPost: alt.home.repair   
   From: wade@cooler.net   
      
   On 3/28/21 10:28 AM, Scott Dorsey wrote:   
   > Xeno   wrote:   
   >>   
   >> Oil in the engine is undergoing a continuous breakdown process.   
   >> Actually, if the truth be known, it is the additives in the oil which   
   >> are breaking down. So, when dealing with oil change intervals, two   
   >> factors need to be considered; additive depletion and oil contamination.   
   >> These are like the proverbial piece of string - there is no hard and   
   >> fast rule on when additives are sufficiently depleted or the oil   
   >> sufficiently contaminated to warrant an oil change. Ditto for the oil   
   >> filter.   
   >   
   > Yes.  In most cases, the VI is breaking down faster than the base oil.   
   >   
   > However, if you're driving an old car with a lot of blowby, you may find   
   > that contamination of the oil becomes a problem before breakdown does.   
   > On the other hand, if you're driving a new car in widely varying temperatures   
   > you may find VI breakdown becomes an issue long before contamination.   
   >   
   >> When I was an apprentice, and later, a rule of thumb, backed by the   
   >> vehicle owner manuals, was an oil change every 5,000 km (3,000 mi) with   
   >> a filter change every 10,000 km (6,000 mi). This was the norm for the   
   >> average 6 cylinder vehicles (GM, Ford, Chrysler) of the day, 4 cylinder   
   >> vehicles had more frequent oil changes.   
   >>   
   >> What has happened since then? Oils (and their additives) have improved   
   >> out of sight. Also, engine ventilation systems (PCV) have improved   
   >> vastly. This has extended the oil change intervals. My car, a Toyota,   
   >> has the oil *and* filter change interval *recommended* by the   
   >> manufacturer at 10,000 km (6,000 mi). So, the oil change interval has   
   >> been doubled but the oil filter change interval seems to have remained   
   >> static.   
   >   
   > Yes, this is true.  Also we have many cars which use an algorithm to   
   > estimate the state of the oil given the time and driving conditions,   
   > and which can more precisely estimate proper oil change intervals.   
   >   
   >> What seems to have been forgotten here is that the recommended oil   
   >> change interval will depend on the use made of the vehicle. If you do a   
   >> lot of short runs where the engine never warms up sufficiently, you will   
   >> experience greater wear factors and increased oil contamination   
   >> requiring shorter than recommended oil change interval. Will that impact   
   >> the filter change interval? Maybe. It really depends on the filter   
   >> capacity - the point at which the filter will block up and commence   
   >> bypass. A large filter of, say, 1 litre (1 quart) capacity might not   
   >> need to be changed more frequently. On the other hand, a small filter   
   >> with half or a quarter of the capacity might need to have a more   
   >> frequent change interval.   
   >   
   > Bingo.   
   > --scott   
   >   
   It's really hard for me to understand why this is such a long thread   
   that includes so many erudite discussions of motor oil chemistry and   
   operation.   
      
   Of course you change your filter every time  you change your oil!   
      
   Here's why:   
   You're already underneath the vehicle.   
   The drain pan is in already place.   
   You already have oily hands and a greasy smear on your face.   
   You've already skinned your right hand knuckles and yelled Damn it!   
   Walmart sells a standard Fram oil filter for $3.88 while Fram's "Ultra   
   Synthetic 20,000 Mile Change Interval" filter goes for $8.57.   
      
   I haven't run the filter/car cost ratio/percentage yet...but I paid   
   $44,762 for my ride...   
      
   --   
   There are no dangerous weapons. There are only dangerous men.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)