SSchulze

My oil level gauge will often read at about 4/5 full when I come to a stop from a long drive and wait a minute or two to let it settle, but then I'll move forward 10 feet or something and the gauge goes to about 2/5 full and stays there no matter how long I let it run. Which reading is correct? According to the manual the gauge is doing all of the things it should do so I think its working fine, but this is a fairly severe slop in readings. I'm terrified of putting in too much oil and terrified of running it too low. Thanks for any advice you can give.

GK

Hi SSchulze,

The oil level gauge is only accurate when oil is hot and engine is idling. As you start driving oil goes into the engine and level shown is low, but it does not mean there's not enough. To check oil level you have to do it yourself with the dip stick, when engine oil is at operating temperature, at least after a 15 minute drive, and with the engine running.

This should be done as often as possible [at every fill up is a good idea]. Also, as mentioned by other members, do not fill it completely as overfilling does not good to the engine. Underfilling by 1/2 quart should be safer, and that's what I do with mine.

Drive safely,

Giorgio.

Randall G.

Hi SSchulze,

You'll want to verify with the dipstick, but you should be fine as long as the gauge needle is out of the red (at idle, engine warmed up, level ground, etc.).

The dipstick is rather difficult to read IMO. You'll want to try and locate the place where oil goes completely around the stick. As the (long) stick is removed, it picks up smear marks that may be mistaken for a true reading.

You might want to consider adding oil in only 0.5 quart increments. The reading on your gauge only represents about 1.5-2 quarts, and seems to be hypersensitive to the last 0.5 quart or so.

Oh, and as per the owner's manual, and per the sticker in the engine bay, the difference between the upper and lower notches on the dipstick is approximately 1.6L (or 1.7 qt.)

Adrian

The difference on the oil quantity indicator between full and red is only 1 litre. This system will only ever be accurate when the 964 is on level ground nice and warm and at idle.
The 911 has lots of oil in it. You need to keep an eye on the dipstick but unless you are blowing smoke or dripping oil on the floor (stick your hand up under the rear engine cover if still installed and check for oil residue, check the exhaust pipe for oil residue, if it is burning oil there will be some oil still in the pipe) the oil will easily last 15,000klms-20,000klms. My C4 was reading red almost all the time, just out of the red on level ground at idle. I got around to checking it at 15,000klms since last oil change and I had used 1 litre. I understand dry sumped engines so I do not personally worry about these indications.
If you have any concerns check the oil every 1000 miles or so but as I said unless you can see you are losing oil do not panic and certainly do not be terrified.
Ciao,
Adrian
911C4

Richard H

Maybe the Oil level sender in the tank is faulty. Mine was rather erratic in that sometimes it would read near the top than read near the bottom. I replaced the sender and now the action of the needle is very smooth and reads pretty much the same level when checked correctly.
Just a thought.

Richard

Adrian

I would start by looking for contaminated connectors and loose connectors before changing the sender.
The instrument damping can also fail. There is a point in the oil level that all 964s tend to huint around a bit anyway. The oil sloshing around in the tank once it is full of air (a dry sumped engine problem). The oil tends to foam up.
Unless it really annoys I would not worry about it. I would not replace the Sender until it has pegged out at max or min and jumps between the two,
Ciao,
Adrian
911C4

Richard H

Maybe my post was a bit misleading. The reason I changed the sender was that it would not rise much above the first mark on the gauge regardless of oil level in the tank. This started after the erratic behaviour on the gauge!
Certainly would not rec. changing the sender before checking all other possibilities or taking the sender out and checking a smooth change in resistance with a meter when the float is moved.

Richard