dave williams
hotrod list  08-19-92
- I just came across an ad for oil analysis.  Supposedly, you send a
  sample of your crankcase drainings to this place, and they tell you all
  sorts of Mysterious Secret Things about the inner workings of your engine.
- Thinking about it for a minute, it looks like they could spot
  combustion products, metallic debris, water, and worn or overheated oil.
- Combustion products are from blowby.  A manometer will tell you how
  much blowby you have.
- Water would indicate a head or manifold gasket leak, cracked block or
  head, or other trouble.  Or it could simply be condensation, which
  happens a lot to race cars that sit for a week at a time.  Enough water
  to make any difference would be obvious, or so I assume.
- Oil lubricates by attaching long chemical chains to the metal parts.
  Other long chemical chains slide around on them.  New oil has long
  chains.  As the oil gets old, these chains break down from heat or
  simple mechanical tearing.  The lifters, valve stems, and timing chain
  can do this.  If you knew how long the oil had been in the engine, you
  could possibly tell if you had a borderline lubrication problem.  Most
  race engines do - those mentioned above, only worse.
- Oil can be overheated; either through overwork (see above), or by
  excessive heat from the pistons or exhaust valves.  Burned oil is like
  worn oil, only much worse.
- Engines generate metallic debris all the time.  Pieces of cylinder
  wall, ring, cam, lifter, rockers, you name it.  New engines make a lot;
  broken in engines much less.  On an all-out race engine, the sudden
  appearance of *new* debris - tin, iridium, or silver - might indicate
  your bearings were going away.
- Unfortunately, as I see it, most motors would either fail or be rebuilt
  before an oil analysis would mean much.  Unless I've missed something?

[email protected] (Dave Williams)
Ford  08 Nov 1996
- -> How do you -know- it's good for another 3K miles?
- Oil analysis will tell you.  However, oil analysis costs $15-$25, and it 
  costs me .89x5+1.75= $6.20 to just change the oil.  With big trucks or 
  industrial equipment that might use 20 or more quarts of oil and a $20 
  filter (or two), or a fleet situation where you can get a special deal on 
  analysis, yes, it becomes practical.  For an average owner, it's just a 
  curiosity.  For a racer, it's worthless. 
- -> >  I even hear that manufacturers are already looking into a sealed
  -> crankcase >to be filled with an oil that will last 100,000 miles.
- > Fine.  I've got a drill and a tap&die set to take care of that.  How
  > do they intend do get rid of all the crap from the break-in period?
- GM is already doing this with their new front-driver transmissions, used in 
  the "look at me, I'm a moron with the headlights wired on" cars. They claim 
  there are more problems from people getting dirt in the oil through the 
  dipstick tube than there are just sealing the thing up. Since 99% of people 
  couldn't identify a transmission dipstick to save their life I find their 
  reasoning doubtful. 
- This all presupposes they've managed to create an FWD transaxle that leaks 
  NO fluids from any of its myriad seals, gaskets, and O-rings.   I predict windfall profits for 
  the sleazy transmission repair places in a few years. 
- Hell, I don't even *own* a four wheeled vehicle with less than 100,000 miles 
  on it.  The lowest mileage in the CarFleet is somewhere around 160K.  I 
  don't find a 100K lifespan all that impressive.