Porsche recommends multigrade oils in all the owners manuals. Definitely flow is important hence the pump but viscosity is vital or we could just use high flow water.All multigrades are never thicker than the lowest number even when hot so your choices for cold starting is either 5 to 20 weight. The important number is the second number that the oil maintains that of its comparable viscosity when hot.
(excerpt)
[ For all year round filling (oil change intervals 15.000 miles/24.000 km) use multi-grade oils
SAE 10 W-40, SAE 15 W-50 or 20 W-50. The 20 W-50 oil should not be used at constant
temperatures below + 5° F/-150 C.
Porsche recommends the use of single-grade oils only if multi-grade oils are not readily
available. Oil changes must then be performed according to season to guard against engine
damage. The following viscosity can be used: in summer SAE 30, in winter SAE 20 W (only
at constant temperatures below + 41° FI + 5° C).
Porsche does not recommend the use of oil additives.
E n g i n e Oils — petroleum based and/or synthetic based Always use quality oil labeled "API Service SF or SE" which has been approved by Porsche.
The terms SF or SE may appear on the oil container singly or in combination with other designations, for example: SE/CC, SF/CC or SF/CD. Engine oils are graded according to their viscosities.
The grade to be used depends on existing or anticipated seasonal climates. Refer to the
temperature chart when selecting engine oil. If you need to add oil, it is permissible to mix oil of different viscosities. As the temperature ranges for different oil grades overlap, brief utside
temperature variations are no cause for alarm. When using SAE 10 or SAE 5 W-20 engine oil.
avoid high speed long distance driving if outside temperature rises above the indicated limits.
Single grade oil
Porsche recommends the use of single grade oils only if multi grade oils are not readily available. However, engine oil changes must then be performed according to seasonal temperature changes to guard against engine damage.
Multi grade oil
For all year round driving use multi grade oil. Oil change intervals specified in the Warranty &
Maintenance brochure accompanying the vehicle must be adhered to, including intervals
for oil filter change.
Fuel-efficient-oil
For all year round driving a top quality "Fuel-efficient"- oil can have a beneficial influence on fuel economy. Before selecting these unconventional oils, consult your Porsche dealer. ]
see page 102 in the 84 owners manual .Not all the manuals have the chart.
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