Mobil 1, which viscosity? Hard start cold

["Scott M." <scottmo@teleport.com>]

Marlaine,

Last summer I started running synthetic oil in my 89 200TQ,
initially I was using Castrol Synthetic 5W-50 but switched
to Mobil 1 10W-30 in the fall. The winters in Portland, OR
are pretty mild with daytime temps in the mid 30's during a
few months. When spring time rolled around I decided to
continue to use the 10W-30 as suggested by a friend who is
an ex GM training instructor. Apparently GM recommends
10W-30 year round in many applications.

I modified the EPROM code in my ECU and am currently
running 1.8 bar boost (brief overboost to 1.95 bar). The 
engine normally uses around 1 Qt per 1500 miles when
driving the car around town to and from work. 

Last month during my  road trip (5300 miles) to Virginia
City Hillclimb and to the Pike Peaks race I drove through
Death Valley during a mild day (only 115 degrees F) and the
oil pressure never dropped below 3 bar driving 70-80 MPH
with the A/C going full tilt and oil temps slightly above
130 degrees C. The 10W-30 synthetic oil seems to be more
than adequate for the summer months. The interesting thing
was that during the last part of my trip the engine only
used 1 Qt in 4000 miles of hard driving. 

Even during a 110-130 MPH blasts at 6,000 foot elevation
and 80-100 F degree outside temps the engine worked fine
with plenty of oil pressure. Others may disagree but I
don't think the higher weight synthetic oils are needed.
The thinner the better..........is my motto.....I don't
like driving around with the oil pressure gauge needle
pegged over 5 bar for too long........YMMV

Regarding your hard start when cold problem, you may want
to have your injectors tested for leakage, my car had this
problem, changing the injectors improved the starting
immensely. This is of course assuming that the other  fuel
system components check valves are holding pressure after
the engine is shut off and you have no vacuum leaks and the
basic idle mixture is set to 0.6 - 1.2 % CO.

Cheers
Scott M.