ORIGINAL: lookingfora944
One thing though, bearing in mind I had it serviced 3 weeks ago, the oil light came on after I started this morning and it's been on ever since. The pressure has dropped to about 4.5 bar when driving and about 3 when idling. Though the dipstick says it is full. Unless I am reading it incorrectly. Should you take measurements when the engine is hot/cold? I guess I should add some anyway, but how do I know how much to add if it's supposing already full? And what if I add to much?
Dipstick measurements should (I think) be taken with the engine off and cold, and the car on a level surface. And, as has been said, take care not to over-fill - that is bad. I find that, on my S2, it doesn't take much oil loss to cause quite a large drop on the dipstick; it can look a good 1/3 of the way down, but 250-300ml will have it up to the top again, so go easy when topping it up. If you DO over-fill, you need to take some oil out; suck some out of the dipstick tube or the filler pedestal if you have a syringe and tubing, or take the drain plug out briefly.
Oil pressure is much debated. The only definitive thing to say is that it shouldn't drop below 0.5bar. Your pressure measurements sound very normal, but providing a comparison with other cars is slightly meaningless as there are so many variables; how hot the engine is, how long it has been driven for (and how hard), what the amibient air temprature is and what sort of oil you have in the engine, to name a few. The best advice is to keep a weather eye on the gauge, and if it seems to be dropping over time (i.e. it is generally lower, situation-for-situation, than it was six months ago) then think about investigating it. And, clearly, if it suddenly drops while driving, then stop the car and turn the engine off.
Oli.
ETA: The oil level warning light often seems to give a false reading on 944's; mine comes on when the oil is about 1/3 of the way down the dipstick, and often even less. And it sounds like this is a fairly common problem. I suspect that the float on the end of the level indicator probably leaks over time, and thus doesn't float as well as it should, and hence gives artificially low readings, but that's just a guess. Driving your car with a big red warning light illuminated on the dashboard feels very wrong, but if the oil pressure gauge is showing a good reading then don't worry too much about the light; just top it up next time it's convenient.
