neanicu

I've been noticing this ever since I got the car but never been so particular to worry about every little detail : when you start the car after it's been sitting,the oil pressure gauge is at 0 for just 2-3 seconds...not even...and then it jumps to where it should be. I'm not trying to bring up the subject about a malfunctioning sender,which has been discussed a lot here,this is not the case. This is normal behavior and it probably needs those 2-3 seconds to build oil pressure or the sender reacts with a short delay.
I agree it is good practice for those that DIY their oil changes to put some fresh oil thru the filter housing,then remove the fuel pump fuse and crank it over a few times to build pressure.
When the car has been sitting for a while and all the oil drained back into the tank,I suspect building some oil pressure just like you do after an oil change would be good practice as well.
This is my idea : if you put your accelerator pedal all the way to the floor and crank it over,in most cars,this will put the computer in " Clear Flood Mode ",which basically cuts all injectors from spraying any fuel. So the engine will crank over without starting. This way oil pressure will be built. The only thing I don't like is that spark going nowhere...
Any thoughts on this?

Daytonaman

My thoughts are that P-Car engineers aren't worried about startup oil starvation; there is oil flowing immediately out of the pumps even tho it hasn't built substantial pressure. Oil clings to frictional surfaces a long time.
Besides, I run Motul 20w60..*
*Not recomended by Porsche.

Macster

Yeah. Relax.

Actually time the amount of time the oil pressure remains at zero. I think you'll find the time is less than you think.

Where is the oil pressure sensor located? Probably a ways from the pump, and the bearings so by the time the gage reacts oil flow and some pressure have been present at bearings for some time.

Any air in the oil passages has to be pushed out and during this time oil pressure reading will be low, maybe even non-existent, as the air will not develop any pressure ahead of the onrushing oil, it just leaks out and is replaced by oil which being much more viscous and thus able to develop pressure in the confined spaces.

But there is oil pressure at the critical points or the engine would be worn out after just a few starts. (How many cold starts do you think for instance my 110K mile 03 Turbo engine has experienced? Yet hot idle oil pressure is just fine thank you. How many cold starts do you think the Turbo with over 350K miles has had? Or my Boxster with just under 270K miles?)

Remember too the oil pressure needs of the engine at a cold start are low. Cranking speed is IIRC around 75rpms. The engine starts and obtains a 1000 rpm idle. That's just 16.7 rpms per second. It also of course spins the oil pump at 1000 rpms.

There's plenty of oil at cold start. If you remove the fuse or floor the gas pedal on the assumption the e-Gas believes this is to clear a flooded engine and the engine controller does not trigger spark or fuel injector pulses (I'd not make this assumption) the engine still has to crank with whatever residual oil is present. The only difference is it now cranks at a much lower rpm.

There are at least two things wrong with this. One is the bearings are hydrodynamic. The oil film that is created and prevents metal to metal contact needs some rotation of the bearing journal to be created. With low speed running with the starter this may prevent or delay the oil from forming a film that is sufficient to protect the bearing surfaces from metal to metal contact.

I note too Porsche (along with every other car maker) always has the cold engine idle speed above the hot idle speed and there is no delay in getting there. If cold start bearing wear and oil flow was such a concern you would think Porsche would delay the rise in engine rpms to allow the oil to flow.

Avoid the urge to switch to a thicker oil. All this thicker oil does is delay the cold oil flow to critical areas and until up to full operating temperature this thicker oil may not flow as readily to bearings (and out again people forget that part) as the oil of a proper viscosity grade. Not flowing to critical areas the downside is obvious. But a too thick oil may actually run hotter in the bearings as the thicker oil generates considerably more heat due to the friction of the oil. But being thicker can't flow away from the bearing as it should to carry this heat away.

About all I can add is if you can't or won't use the car more often and are concerned about cold starting consider adding Swepco 502 oil improver. The Porsche techs advise this for customers who do not use their cars very often. As I mentioned before I tried some in both cars but didn't notice any reduction in start up noise. But I use my cars often. Except for vacations when one car gets parked a week or two both cars get used every few days.

Regardless of anything else change the oil/filter at reasonable intervals. I do notice a considerable reduction in engine noise (at cold start) after an oil change and this is with oil that has only 5K miles on it. Even given my regular usage in 5K miles the oil gets diluted enough that the engine is a bit noisier towards the time the oil is due to be change.

And relax.