When we bought our SAAB 9-5ng I knew it has an oil pressure issue, but it was told me that it has to do with the sensor. Well it has nothing to do with the sensor, since the oil pressure is just too low. Starting cold the oil pressure is less than 1 bar and when you add some gas it raises to 1 bar. Above 1 bar it is ok for the sensor, but it should be more.
What part do you need to replace
It is necessary to replace an o-ring with the number GM 55589549.
It is not a SAAB number, so be sure you order an o-ring. This o-ring is placed where the oil suction pipe goes into the motor. So it is not an easy replacement since you will have to lower the sump. As I did not do it myself, I have no experience what you need to dismantle to replace the o-ring.
Is it solving the oil pressure issue
Yes it is solving the oil pressure issue. After replacing the o-ring the dealer measured the oil pressure at cold start and immediately it was at 5 bar! You can also feel that the old part is hardened.
At what interval the o-ring has to replaced
At latest you will have to replace the part immediately if you have a warning when you start the car. According to others there seems an interval from Opel where they say every 120.000km. But I have also read from people they are only at 60.000km. So it depends alo on the kilometer or miles you drive per year. For myself I will use the interval 120.000km or 5 years. So mine was replaced in January 2016 at 192.500km and I plan a replacement at 300.000km since we drive around 27.500km a year. (Then I also need to replace the timing-belt, so it will be a big operation at once).
There are risks when you do not solve an oil pressure issue
The previous owner already had replaced the Turbo on our car. And driving with this continue low oil pressure can ruin your engine totally!
Which oil is used
According to Beherman (ex SAAB importer for The Netherlands and Belgium) it needs 0w40. Mine is now running on Mobil 1 New Life 0w40 (fully synthetic). Maybe next time I will use Mobil 1 ESP which might be better for driving the car a long time.
Since I wrote this article I got some comments from people who said that there are better oils available today. It seems that Dexos2 0w30 or 5w30 has the high shear module as a modern diesel need, but it has also a lower friction. I have no experience with an Dexos2 oil, but I will take a look and will write here my experience.
Which engines this issue involved
For SAAB the only engine is the 2.0TTID which can be found in the 9-5 from 2010 and later. There are other GM products like the Opel Insignia which has the same engine and this issue.
As mentioned in the start of this post our 9-5ng had this issue when we bought it. For all the details about our 9-5ng, see the post Our SAAB 9-5ng and why did we bought this specific one.