Birdman 996

I would like to know what average oil pressures folks are seeing with their early model 996s or Boxsters, i.e. up to 2004.

If you could give me Idle, 2000 rpm, 3000, and 4000 on a warmed up engine I'd really appreciate it.

Thanks all.

Macster

Why are you asking about oil pressure? Just curious or...?

Don't have an oil pressure available for my 2002 Boxster. But I can tell you even after over 315K miles and even in triple digit ambient temperatures with the coolant temperature at (a constant) 226F (fans running on high constantly) even at idle I never got a low pressure warning light.

My 2003 Turbo with just over 160K miles has been pretty consistent with its oil pressure, although there is some variation in the hot idle oil pressure depending upon ambient temperature. The engine cooling is very good but the engine does run a bit hotter in high ambient temperature and the oil is hotter too, of course. The lowest I've seen hot idle oil pressure go is 1.5 bar as shown by the oil pressure gauge in the dash/cluster.

At 2K RPMs oil pressure is pretty close to if not over 3 bar and at something over 2K and beyond oil pressure is definitely 4+ bar per the instrument cluster pressure gauge.

The factory only specifies oil pressure at one RPM and with the engine hot. Approx. 6.5 bar at 5K at 90C. The oil pressure gauge only goes up to "5". There is no "6" hash mark. At red line I've never seen the oil pressure reach the "5" hash mark. It goes up a bit past the "4" and thats as far as it goes. I don't believe the engine oil pressure is low. What is more likely is the oil pressure gauge is just not a precision gauge. Based on my experience with real oil pressure gauges engine oil pressure is very dynamic and if the oil pressure gauge displayed true oil pressure in "real time" most owners would freak out.

Might mention I used to run Mobil 1 0w-40 in both my cars. A while back I switched to Mobil 1 5w-50 (not a typo for 15w-50!). While it doesn't get that cold here -- has gotten down to "just" 32F a couple of nights so far this year but it doesn't stay that cold but only for a short time then -- just touches it then starts to climb again -- and by mid day it is up to 60F -- it gets plenty hot. Triple digits any time between late June to October are possible.

Anyhow, based on my Turbo's oil pressure gauge I can't tell which oil is in the engine. The oil pressure reading is not up with 5w-50 or down with 0w-40. This makes sense in a way as both are approved oils and both deliver the viscosity that Porsche has deemed ideal for the engine.

Birdman 996

Thanks for comprehensive reply Macster.
The reason for the original question was concern with HIGH oil pressure. My son bought a '99 911 (996), which as I understand it has the same basic engine as that year 986, so I posted on both forums. The car's oil pressure runs above 5 bar at RPMs greater than 3000, the needle is basically pegged. I've been worried that the oil pressure relief valve is stuck and the pressure may be too high for the health of seals and o'rings; so am asking for feedback on the norms out there. (Replaced the oil pressure gauge sending unit last week and still have identical indications.)

Macster

If my Boxster factory manual has an oil pressure call out I don't recall it. But 5 bar ain't that high, just 72 psi. I posted the factory oil pressure call out for my Turbo and it is approx. 6.5 bar at 5K at 90C. That's 94 psi. No seals or o-rings have blown out yet. Really no seal or o-ring has to hold that pressure other than maybe the o-ring for the oil filter housing. And that o-ring is captured in an o-ring groove. All the other seals are metal to metal fits with Porsche sealant spread out in a very thin -- zero thickness actually -- layer. I'm talking the crankcase halves and the camshat covers to the heads. In both cases high pressure oil galleys, passages, and oil holes are sealed against leaking. If something was going to leak you'd know it by now.

Are you sure the gauge you are using to measure oil pressure is giving you accurate results? Typically oil pressure gages fitted to production cars suck. They are little bettter than idiot lights with some movement.

Birdman 996

Thanks again Macster, More good info. It would probably be helpful to tap in a quality test gauge for an accurate check. But from what you are saying I may be overly concerned with this issue.

Anker

In all cars there's an oil pressure relief valve in the oil pump. If the pump is working well you will typically see constant pressure as soon as the oil is warm or hot. Low oil pressure can be the result of a bad oil pressure relief valve, a badly work oil pump or bearings that are so worn that the pump can't deliver enough oil to the bearings to maintain pressure.