Original thread at http://tinyurl.com/bn5kp,
and http://tinyurl.com/ayf7j before that.

History: My original engine (97 tercel, 120,000km or 75,000 miles)
sprung an oil leak and I burned it out.  A used engine of similar
mileage was put in, and it burned oil in well in excess of what my
mechanic thought reasonable, as well as exuding a lung-aggravating
scentless fume.  It has been replaced by a 2nd used engine of similar
mileage, along with a new rear main seal.  Prior to this 2nd
replacement, the 1st used engine also leaked at the rear main seal,
enough to leave oil drops on the gound, and the oil smell was
overpowering.  Replacing the oil pan gasket seemed to reduced the oil
fumes significantly; it didn't reduce the oil loss, and the scentless
aggravating fume was still present.

The mechanic put in the 2nd engine because of the oil loss in the 1st
one; I was more interested in getting rid of the aggravating fumes,
which makes it impossible to drive without all windows down (bad in
winter, rainy days, and hot days).  The 2nd used engine doesn't lose
oil at a significant rate, but there is an overpowering oil smell
similar to that in the 1st used engine before the oil pan gasket was
replaced.  As well, there are oil drops on the ground.  I had my 1st
look underneath today, and saw some seepage at the rear main seal, and
minor seepage at the front mail seal.  The rear main seal is
supposedly new.  There is also 2-inch diameter dent in the oil pan, at
the corner (so it bulges inward instead of outward).  There is surface
rust on the dent.

There is no significant oil loss in the 2nd engine, but I'm concerned
about the impact from breathing the fumes from seeping oil on hot
engine surface.  Whenever I work out, I cough vigorously, and fellow
exercisers remark (jokingly) that its from all my smoking (I don't
smoke).  I have been told that changing the rear & front main seals
involve significant work.  What is reasonable to expect of my
mechanic, considering that the rear main seal is new, and it still
leaks?  I don't want to be unreasonable, but neither do I want to
continue breathing the fumes.  I can't tell whether the scentless
aggravating fume has been eliminated when the overpowering oil fume is
present.  (It is also possible that the "scentless" aggravating fume
in the 1st engine is really due to the a much smaller amount of engine
oil smouldering compared to before the oil pan gasket was replaced).

What about the 2-inch dent in the oil pan?  Is it it a minor issue to
replace oil pan whent the rusty dent rusts through?  Is it OK to
ignore the possibility that the engine might have some other problem
due to such an impact?  Is it reasonable that I was not informed about
this rather dramatic dent?

Thanks for your experienced opinions.