Ed Hughes

And then when you get to learn your car and it's oil consumption, that desire or need to check after each drive goes away.

Steam Driver

Why is it necessary to have the front cooler T-stat open? Those lines are full oil all the time, are they not? So they would have no effect on the level in the tank.

Ed Hughes

They aren't full after sitting

ron mcatee

It's a dry sump system. Circulating oil when the thermostat opens will give you the proper level reading. I changed my oil in the 88 Carrera yesterday and can verify that the difference is about 1/2 to 3/4 of a quart of oil (on my car). I always run it mid-level on the dipstick and use the guage to substantiate it, but have never used the guage alone.

theiceman

EXACTLY

dry sump system in the Porsche uses a dynamic oil level check which includes thermostat open ( engine warm ) and oil cycling through the system ( engine running)

has very little or nothing to do with volume of hot oil vs cold oil itself. .

bgiere

engine at operating temp, 190ish, middle mark on temp gauge. Let the car idle for 20-30 seconds on level driveway. read dipstick. I run mine at half'ish...my gauge always matches the stick. I have done it thisi way for the 23 years I've owned my Targa...never overfilled it. I don't know how to get an accurate read if the car is not up to temp.

Mark Salvetti

If the front cooler T-stat is closed, doesn't that trap all the oil in the cooler lines? Even the return line from the front cooler passes through the thermostat. With the T-stat closed, I don't think the lines can drain.

To me there are two reasons the engine has to be at operating temp. On initial start, the rpm of a cold engine is higher than hot, so the level in the tank reads low. Then once the rpm has dropped from the cold start, you want 180-190F to get the most accurate reading to allow for expansion. I think from 70F to 190F the oil will expand about 5%. Not a lot if we're talking 4 quarts, but with our 12 quarts that is slightly over 1/2 quart. Volume matters - if it didn't then running the engine with just 6 quarts wouldn't show a low reading on the dipstick. If the level on the dipstick is low, we had another quart - volume.

When the engine is off, the oil level in the tank and the engine case equalizes - there is more oil in the engine than normal, so the tank reads very low.

If the oil in the front cooler lines is trapped (i.e. the same amount of oil is in the lines hot or cold), engine rpm is around 900, and the oil pump is scavenging oil from the engine case, then the dipstick in the tank is going be pretty close even when the engine is cool - probably about a 1/2 quart low because the oil isn't warm and hasn't expanded. It's not because the T-stat to the front cooler hasn't opened.

Mark

Ed Hughes

T-stats don't snap shut when the motor is off. Sure, a good amount of oil stays, but I always hear gurgling when it opens and oil flows. It really is "all of the above" when one checks oil on a fully warmed engine vs a cold one.

Mark Salvetti

Ah, very good point. Hadn't thought of that. Thanks Ed.

DanS911

And that's all there is too it.... next lesson is on how to properly operate the heating and defrosting system...;-)

gerry100

I check it in the garage after we've had a good workout.

NEWBIE - Don't drop the dipstick in the filler neck! Carefully place it the tube inside the filler neck.

fpb111

With the others.

TheMystro

I have done this for 20 years. It takes a long time for oil to warm up in a 911 when just idling. It seems counter intuitive to check your oil after the drive but nothing on a classic 911 is like other cars.

Pavegeno928

Shoot, I drove my car for a few hours this weekend to and from the Black Forest from Stuttgart and couldn't get the temp above the first mark...turns out cruising at 120 mph does wonders for the oil temp. Guess I just have to hope my oil level is good.

JonSnow83

There's a proper way to do this? I just mash the levers around blindly until something resembling the air temp I want comes out of a vent somewhere...

A manual in English might have helped, but the system has worked so far