How reliable is the oil level indicator? I have driven about 4000 miles since my oil change and the level indicates it is full. Any way I can manually check the level?

 

Yeah, if you change your own oil you can measure the amount of oil you drain and add about .5 for "trapped" oil and compare that to what the indicated level was.

Jason

 

There isn't a way to manually check. But I do suggest to take multiple readings using the electronic gauge. Angle/pitch of the car makes a big difference, cooldown times (regardless of what the meter 'timer' says) makes a difference. Unless you see something extremely out of range, I'd take four or five readings before making a decision to add (or remove) oil. But don't wait too long.

 

I know a liquid crystal bar graph on the instrument panel seems distant from the physical reality of the oil reserve, but it isn't really. Whether they use a capacitive sensor or a conductive one, an electronic sensor is still as reliable as the sheen of oil on a probe. Arguably more reliable, and certainly more accurate and repeatable, for several reasons too arcane to discuss, but including at least three kinds of operator error that occur to me offhand.

A mechanic can insert a probe, but he has to know things we do not. Particularly, what distance from the lip of the orifice the oil should be when full.

I hear a lot about this, EJ, so forgive me that I picked your post to finally say something: speaking as an engineer, the classic dipstick has been growing problematic for at least the last decade or so. Even the engine designs of the seventies had begun to show problems. These are not flathead Ford engines from the thirties.

Very few cars have a wet sump configured so the probe can enter from above and reach a central deep portion to get a level that is not over-easily influenced by the deck angle of the car. The sensor on my 997.2 is consistent, and so located in the engine that it takes a deck angle of about fifteen degrees to change the reading by even half a bar segment. Depending on a display choice we don't know, that is either six or twelve ounces of precision. Six, if I had to guess. Either is far more precision than we need. I remember my small-block Chevy V-8 had a dipstick you couldn't 'dip' at all. You fed it in like a roto-rooter, trying to avoid kinks, because it was over eighteen inches long and took at least one significant turn to reach the oil sump. Even doing everything right, you were lucky to read that stick to half a quart on a good day. 16 ounces that is. So we haven't lost anything. Especially because either method of measurement is intended to give a binary result: "Add oil." Or "Do not add oil."

Dry sump engines are better if they simply have a physical can of oil bolted somewhere near the engine, because hypothetically you can just shove a stick into the top with calibrated marks. In a car with an engine compartment as confined as the 911, even that is a challenge sometimes. It forces the designer to put the oil tank somewhere accessible from above, or add an extra door in the body panels, as they did in one body version. That isn't always the most desirable location of the sump for other purposes.

It did catch me aback when I first realized there was no dipstick on my 997.2, until I considered all these issues. It does have a dry sump, but the "can of oil" is actually part of the crankcase casting and this is an engine that pushes the boundaries of power per volume in the chassis more than any other I can think of offhand. The bodywork does not open half the car the way a Corvette, an Aston Martin and many Ferraris do. We just open a panel the size of a suitcase lid. Personally, I am quite happy they did not impose a pretty much irrelevant requirement on the engine designers: "Keep a vertical access somewhere for a probe that can reach the oil sump." These days, that is about as useful as requiring a little man to walk ahead swinging a red lantern.

All it would achieve is cutting down on the discussions at on-line forums. Would that be that fair to 6speedonline and Rennlist?

Think of it as a form of Porsche incentive package to the list.

Gary

 

Good timing on the question.

X-post from rennlist -> we don't need dipsticks because we are

If you read the article - scroll through the comments...it makes for a good laugh