Oil Viscocity Problem?

[skandalis447]

Hello there...i bought my car with 23500km...Previous owner used mobil1 0/40 until 20000km (he changer them at 7,14)and then replaced them with redline 5/40...i switched back to mobil at 26000km,two weeks ago...The problem is tha when i start the car after a few days of garage sitting it makes a horrible noise (probably from lifters?)such as there is no oil for about 1/3 of a second and then oil pressure goes up and the noise stops...engine is running fine...With redline this noise did not happen...any ideas?

P.S. the car has almost no oil consumption...this happens only when car is parked for a few days...

[Loren]

5W-40 Mobil 1 is also an approved oil so you could try that.

[skandalis447]

thank you loren...but what is your opinon on that matter?

[Loren]

I use mobile 0W-40 but when my car was new Porsche recommended (at that time) 15W-40.

A little tapping for 30 seconds or so does not hurt anything - it is just that oil drains out of the hydraulic lifters after some time.

[skandalis447]

thank you again Loren for your time to answer me...the noise is for about half second...i thought of it this morning.It happened same time when i changed a coolant hose that was leaking (you might be aware that 997TT have a failure at pressurised coolant hoses near the thermostat assembly...)in order to change these hoses,oil filter base had to be removed.probably sealant had failed allowing air to enter oil filter housing after a few days...the noise is the same when we start the car after we ve changed filter for a second,until oil is pressurised again in filter...