Oil question...
Thread Starter
Race Director
Joined: Apr 2003
Posts: 19,347
Likes: 654
From: Tampa, Florida
Oil question...
The current 'self destructing' thread has me thinking.
How much of a difference is there on the dip stick when checking oil level warm versus cold?
Anyone have a picture of the dip stick?
If oil level is checked cold it can artificially read low because oil drains out of the tank. So wouldn't topping off low cause the system to have too much oil?
If the car really is low with a seized engine is it because they refilled without running the engine and circulating the oil through the system first?
How much of a difference is there on the dip stick when checking oil level warm versus cold?
Anyone have a picture of the dip stick?
If oil level is checked cold it can artificially read low because oil drains out of the tank. So wouldn't topping off low cause the system to have too much oil?
If the car really is low with a seized engine is it because they refilled without running the engine and circulating the oil through the system first?
Last edited by jim2527; Sep 26, 2016 at 10:04 AM.
Drifting
Joined: Jun 2007
Posts: 1,425
Likes: 238
From: Macomb MI
You seem to be referring to a C7 dry sump? Assuming so, most folks who have run experiments on "cold check" dry sump oil levels report that given enough time (hours), a properly filled C7 dry sump will eventually show no oil on the dipstick.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
You seem to be referring to a C7 dry sump? Assuming so, most folks who have run experiments on "cold check" dry sump oil levels report that given enough time (hours), a properly filled C7 dry sump will eventually show no oil on the dipstick.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
The guy doing the oil change didnt drain both plugs, and put WAY to much oil in.
Drifting
Joined: Jun 2007
Posts: 1,425
Likes: 238
From: Macomb MI
Sounds vaguely familiar now that you mention it. I think there was also something more recently with the "one plug drain" (but no lock-up) in the Z06 section. But going back to early MY14 we were in the throws of oil foaming and dripping filters as well...so my memory is cluttered with oil stories.
Thread Starter
Race Director
Joined: Apr 2003
Posts: 19,347
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From: Tampa, Florida
most folks who have run experiments on "cold check" dry sump oil levels report that given enough time (hours), a properly filled C7 dry sump will eventually show no oil on the dipstick
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it..
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it..
Any guess as to how much oil would need to be added to a 'cold check' so it would read as 'full' on the stick.
1 quart? 3? 4? 6?
Team Owner
Joined: Sep 2014
Posts: 26,430
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I will try cold after sitting over night, cold after short run to bring oil pressure up and then shut off and finally normal, after oil temp above 175 F.
Cold after sitting over night is way low, about 1 1/2" from bottom of dipstick.
After sitting over night and short start up to bring oil pressure up, just above the hash marks, say 5/8 the way between low and high.
Warm above 175 F after waiting 7 1/2 " from shut down, oil level 3/4 way between low mark and full mark
It appears the oil level grows a little between start up and operating temp, but not much maybe the equivalent of 4 oz.
I wonder where the guy is that gets all butt-hurt without pictures?
Cold after sitting over night is way low, about 1 1/2" from bottom of dipstick.
After sitting over night and short start up to bring oil pressure up, just above the hash marks, say 5/8 the way between low and high.
Warm above 175 F after waiting 7 1/2 " from shut down, oil level 3/4 way between low mark and full mark
It appears the oil level grows a little between start up and operating temp, but not much maybe the equivalent of 4 oz.
I wonder where the guy is that gets all butt-hurt without pictures?
Melting Slicks
Joined: Aug 2016
Posts: 2,761
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From: MOUNTAIN HOME Arkansas
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E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
You seem to be referring to a C7 dry sump? Assuming so, most folks who have run experiments on "cold check" dry sump oil levels report that given enough time (hours), a properly filled C7 dry sump will eventually show no oil on the dipstick.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
As such there is no "cold check" protocol for a C7 dry sump, and hence the specifically documented 5-10 minute wait on a warm engine is the only accurate method.
In theory, a person could potentially add enough oil to a cold dry sump system to severely overfill it. Possibly to the point of pushing oil out the PCV burp line into the intake tube. From there, if sufficient in volume, it could be sucked into the engine through the intake manifold. This has been reported from overfill (oil in the intake tube and manifold). I'm not aware of any documented C7 engine "hydro" (petro?) locks from overfill.
Wet sumps would tend to show more oil in the pan the longer it's been turned off.
Oil drains back from the dry sump tank past the scavenge pump gears, which is why the Owner's Manual says you must check before 10 minutes or you'll get a false low reading.
So your question has no proper answer! If you wait for the oil to get cold it will read low! Depends on how cold you want to let it get! The answer then is IT CAN NOT BE CHECKED COLD. As Mirisa Tormei said in "My Cousin Vinny," it's a trick question!
Last edited by JerryU; Sep 30, 2016 at 05:15 AM.
Thread Starter
Race Director
Joined: Apr 2003
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From: Tampa, Florida
Per the above post! For fun, I checked my Z51 oil level several days after the car was parked. There was no oil showing at the tip of the dip stick! Measuring the dip stick and the hatched area, which in 1 inch is a quart, it was at least 5 quarts low in the tank. There is enough left to lub the engine and you can hear oil flowing back to the tank from the pan as soon as the car is started. By the way, checked the oil after I came back from a drive and it was right where I keep it, half way in the hatched area or 1/2 quart less than Max.
Oil drains back from the dry sump tank past the scavenge pump gears, which is why the Owner's Manual says you must check before 10 minutes or you'll get a false low reading.
So your question has no proper answer! If you wait for the oil to get cold it will read low! Depends on how cold you want to let it get! The answer then is IT CAN NOT BE CHECKED COLD. As Mirisa Tormei said in "My Cousin Vinny," it's a trick question!
Thanks.