There a few reasons why I decided to put synthetic in the Westy (after a
10k break in): the synthetic comes in a broad viscosity range of 5W50 which
is ideal for Ottawa in the spring and summer where it can be cool in the
morning and hot in the afternoon. 

Based on a monitoring of the oil pressure
gauge synthetics seem to "shed" their heat much more quickly; ie after a
15 minute shut down oil pressures will be back up where they were at cold
startup, To me this indicates that synthetics may be less susceptible to
"thermal breakdown" which is a standard argument. Of course the
counter-argument is that this heat is passed on to the block - although
the head temp gauge shows no significant difference w/without (this may
change at the margins, ie summer). 

Synthetics are claimed to have better flow characteristics that translates
into better mileage and lower wear
at startup - of these I have no proof but will report back this summer. Of
course synthetics are claimed to leak more for the same reason and again this
has a grain of
truth but only if there is significant sludge in the system. As Joel would
say - if running synthetics make YOU feel better then this in itself is
beneficial. 

Synthetic is about twice the price of regular 20W50 - which
does not mean that I change the oil less often - six months or 5000 miles
seems to be the way to go for me regradless of the oil that is being used. DC

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David Carment
School of International Affairs
Carleton University
Ottawa, Ontario
K1S 5B6
voice - (613) 788-2600-6662
fax - (613) 788-2889
Email address: dcarment@ccs.carleton.ca
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