30,000 mile oil

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> Noticing a buzz on the list about 30,000 miles between oil changes . . .

[snippage]

> Change the oil regularly! On cars that live in damp climates and are driven
> infrequently, change it more often. On cars that are driven hard, change it
> more often. On cars that are driven in dry, dusty climates, change it more
> often.

And change it before laying a car up for any length of time.

> Remember - oil is cheap, engines aren't. How much does the head cost on a
> 20 valve I-5? Now how much to rebuild the bottom end?

a) Ouch! b) It depends - seen the price of the upper big end shell for
an AAN engine?  GBP23+ _EACH_!!!  $200 just for the upper shells.

> Remember also - there are lots of scams out there, preying on the ignorance
> of worried people. The least worst of these scams do no harm (like magnets
> on the fuel line), and only cost money. There are some really nasty ones,
> too. My favorite is the Freon replacement which is mostly propane, and is
> explosive in an accident when the leaking propane hits the hot exhaust
> manifold. . . .

Propane is nasty stuff - the combination of a high specific heat and
a low specific heat of evaporation means that releasing the pressure
on a volume of liquid propane at room temperature results in the
instant formation of a spherical cloud which is explosive at some
point on its leading edge.  There was a major disaster on a Spanish
campsite a few years back.

Another point on oil changes - frequent topping-up (even when it's
_VERY_ frequent) does not equate to a change.  Those I5s that use
a metal pipe to connect the crankcase breather to the cam cover are
especially prone to breather blockage if the oil isn't changed
properly.

It's also a good idea to do a proper flush (not just the additive sort)
every 100k or so.

--
 Phil Payne
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674