packages to choose from: 15,000 miles and 30,000 miles. If you're
asking which SAE or which brand or whatever to match the service
catagory, then a quality synthetic will meet it I'm sure, but if I had
the G35, I'd just use a non-synthetic for the first 500 or so miles and
take it easy. Forget about doing severe driving until you've got
quality synthetic. Don't forget, it's got a tranny that needs good oil
as well.

Well the Owner's Guide is on the Infiniti web site (at least for the 2005).
See http://www.infiniti.com/form/0,,action-ITechPubs,00.html . The following
is from the owner's guide:

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ENGINE OIL AND OIL FILTER RECOMMENDATION
Selecting the correct oil
It is essential to choose the correct quality, and viscosity oil to ensure
satisfactory engine life and performance. INFINITI recommends the use of a
low friction oil (energy conserving oil) in order to improve fuel economy
and conserve energy. Oils which do not have the specified quality label
should not be used as they could cause engine damage. Only those engine oils
with the American Petroleum Institute (API) certification mark on the front
of the container should be used. This type of oil supersedes the existing
API SG, SH, or SJ and Energy Conserving I & II categories. If you cannot
find engine oil with the API certification mark, use an API grade SG/SH,
Energy Conserving I & II or API grade SJ or SL, Energy conserving oil. An
oil with a single designation SG or SH, or in combination with other
categories (for example, SG/CC or SG/CD) may also be used if one with the
API certification mark cannot be found. An ILSAC grade GF-I, GF-II, GF-III
oil can also be used. INFINITI recommends mineral based oils. These oils
must however, meet the API quality and SAE viscosity ratings specified for
your vehicle.

Oil additives

INFINITI does not recommend the use of oil additives. The use of an oil
additive is not necessary when the proper oil type is used and maintenance
intervals are followed. Oil which may contain foreign matter or has been
previously used should not be used.

Oil viscosity

The engine oil viscosity or thickness changes with temperature. Because of
this, it is important that the engine oil viscosity be selected based on the
temperatures at which the vehicle will be operated before the next oil
change. The recommended SAE viscosity number chart shows the recommended oil
viscosities for the expected ambient temperatures. Choosing an oil viscosity
other than that recommended could cause serious engine damage.

Selecting the correct oil filter

Your new vehicle is equipped with a high quality genuine NISSAN oil filter.
When replacing, use the genuine oil filter or its equivalent for the reason
described in change intervals.

Change intervals

The oil and oil filter change intervals for your engine are based on the use
of the specified quality oils and filters. Oil and filter other than the
specified quality, or oil and filter change intervals longer than
recommended could reduce engine life. Damage to engines caused by improper
maintenance or use of incorrect oil and filter quality and/or viscosity is
not covered by the new INFINITI vehicle warranties. Your engine was filled
with a high quality engine oil when it was built. You do not have to change
the oil before the first recommended change interval. Oil and filter change
intervals depend upon how you use your vehicle. Operation under the
following conditions may require more frequent oil and filter changes.

- repeated short distance driving at cold outside temperatures,
- driving in dusty conditions,
- extensive idling,
- towing a trailer,
- stop and go "rush hour" traffic.
- aggressive driving

RECOMMENDED SAE VISCOSITY NUMBER

[Chart ommitted]

SAE 5W-30 viscosity oil is preferred for all ambient temperatures. SAE
10W-30, 10W-40 viscosity oil may be used if the ambient temperature is above
0°F (?18°C).
.....

ENGINE OIL RECOMMENDATION:
- API Certification Mark
- API grade SG/SH, Energy Conserving I & II or API grade SJ or SL, Energy
Conserving
- ILSAC grade GF-I, GF-II & GF-III
- SAE 5W-30 viscosity oil is preferred for all ambient temperatures.
SAE10W-30 viscosity oil may be used for ambient temperatures above 0°F
(?18°C).

-------------------------------------

The maintenance schedule is online as well. From (
http://www.infiniti.com/form/0,,action-IMaintenancePublic_sctid-52045,00.html )

------------------------------------

Preventative scheduled maintenance is an important investment to optimize
the performance, reliability, safety and resale value of your Infiniti.
Scheduling your vehicle's maintenance at the recommended intervals will
ensure your vehicle is running at its best.

Depending on your driving habits and local conditions, you should follow one
of the three maintenance schedules listed below. Use these guidelines to
determine which maintenance schedule to use:

Premium Maintenance
(Every 3,750 miles or 3 months, whichever comes first)

Premium Maintenance is an Infiniti recommended option that was developed for
owners who want the ultimate in preventative maintenance. With this schedule
more maintenance items are regularly checked or replaced than with the other
schedules.

Schedule 1
(Every 3,750 miles or 3 months, whichever comes first)

This schedule offers the same service intervals as the Premium Maintenance;
however, with this schedule there are fewer items regularly checked or
replaced.

Schedule 2
(Every 7,500 miles or 6 months, whichever comes first)

This schedule offers the least frequent service intervals; with even fewer
items regularly checked or replaced.

-------------------------------------------------

The net is, you don't need synthetic oil. Good quality API Certified Energy
Conserving Motor Oil rated SG (an old rating) or better is all you need.
Depending on your driving conditions it needs to be changed at either 3750
or 7500 miles. Personally, I would use anything less than API Certified SL
oil.

Ed