Re bike endurance, it depends upon a) the sooting level and b) the acidity of 
the oil after the allotted oil change period.

On modern engines the blowby past the rings is very low so the soot carry over 
is at a level where the oil can hold it at a safe level.  Modern fuel has very 
low sulphur content so the acidity in the blowby is reduced and so the total 
base number is held within  tighter limits - some wear is due to acid corrosion 
but part of the additive package in the oil is there to combat this effect.  
The additive package also has viscosity improvers that maintain a closer 
control of the viscosity over the temperature range and with age which is why 
the cost of a modern high quality oil is higher and cheap oil can lead to 
excessive wear, i.e. you pays for what you gets!

Interesting to note that about four years before I retired, the target oil 
change intervals for heavy duty diesels in the US was over 100,000 miles and 
when I left in 2003 it was engine life (>250,000 miles), the latter being 
achieved by a special oil top up package of additives at 100,000 mile intervals 
together with significant improvement in the ring design, cooling system 
optimisation, liner finish, improved filtration and oil quality.  This is not 
so easy to achieve on a vehicle with a much greater variation within the duty 
cycle and a lot of cold running such as a passenger car engine.  Cold start is 
where a lot of the acid attack takes place, particularly if the engine runs wet 
for any period.

Hamish
  ----- Original Message ----- 
  From: Matthew 
  To: [email protected] 
  Sent: Friday, December 05, 2008 12:43 PM
  Subject: [Quantum Owners] Re: 2+2 oil selection




  Oil go with that ;-)

  I personally use whatever it is Ford man gives me for a focus RS Turbo.
  Seems to be a little dearer than trade factors or halfords.  However I'm
  taking no chances with my latest engine.  Spending £40 on oil compared to
  £50 doesn't seem to be an economy worth skipping on considering the value of
  the engine itself. 

  I did hear a story a while back (urban legend?) that one of the bike people
  took two identical new bikes and ran them both for 100k miles, one they
  changed the oil every 4k miles the other they didn't.  At the end they
  examined the wear and both were near enough identical.  

  Matthew





  > -----Original Message-----
  > From: [email protected] 
  > [mailto:[EMAIL PROTECTED] On Behalf Of crash test
  > Sent: 05 December 2008 11:31
  > To: Quantum Owners Group
  > Subject: [Quantum Owners] Re: 2+2 oil selection
  > 
  > If you were happy before and it's only due to a fault 
  > elsewhere in the system and not due to lubrication failure in 
  > general then why change.
  > Only my thoughts.
  > > 


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