For a sanity check, a good oil pressure model for the NA 944 is:
P (bars) = 0.0232 * v (cSt) * RPM^0.288
...where 'v' is the kinematic viscosity of the oil at a given temp. According to the
RP data sheet, your current oil is 48.58 cSt at 40 deg.C and 8.5 cSt at 40 deg.C.
Long story short, you can expect an oil pressure of roughly ~1.42 bar when the oil is fully up to temp and the engine is idling at 950 RPM. No bueno, switch to at LEAST a 0W-30 if you insist on a thin-ass oil. M1 0W-40 is a good choice for cold climates, I run M1 15W-50 in Texas with no qualms.
For a cold start, the oil pressure gauge should be pegged, even with the current oil (~8.1 bar). If you aren't seeing that, you have bigger problems that noisy lifters.
(derivation of that equation can be found
here).