INTHERED

When checking the oil level in a Z51 the manual sez to have the car completely warmed up and to wait 5 to 10 minutes after turning the engine off before checking the oil level. Why do I have to wait ? Why can't I check it as soon as I jump out of the car and raise the hood ? I read threads about catch cans and running the oil level lower than normal etc. etc. because it can cause problems WTF is that all about ? My car is almost new I just want to drive it and not have it drive me crazy !

Thanks >>>> Inthered

robert miller

It has a problem with oil getting hot & forming up over into the pcv system & also going back up into the intake. Really bad if you run the car really hard for any amount of time.

Some put up a post in here that the 2016 zo6 cars & I would also say the z51 cars have something just like a catch can. But GM is not calling it that.

Plus alot of these motor have a problem with the 8 little holes being round in the block & having a lot of blow by from that also..Plus with this problem being worse at the bottom of the holes being out of round.

TBD

...you have a dry sump oil system.

Peace, out.

TBD

Incorrect.

Blue Demon

A little time is required for the oil to get back into the sump.

TEXHAWK0

I don't think oil can drain back to the sump..it has to be pumped both directions, to the engine and back to the sump...

xp800

I honestly have never noticed much difference in checking oil at 1 minute or 5 minutes. On either my 2014 or 2015 Z51. I never waited longer than 5 minutes because any longer than that and I'd forget... And eventually the sump empties below the dipstick if you wait too long which also keeps me away from the 10 minute idea.


Wow. There's so much wrong there, don't even know where to start.

Oil foaming is a byproduct of the silicone curing process degrading the anti foaming agents in the oil in the dry sumps. Follow the break in procedures, change the oil at 500 miles, and it's a NON ISSUE. NOTHING to do with running it hard afterwards.

Liquid oil in the intake tube is from the dry sump burp line, not the dirty side PCV vent that catch cans hook into. And oil foaming only happens on dry sump factory fill oil run hard -before- the first oil change. It is the cause of 90% of liquid oil in the intake tube. The other 10% is from SEVERE overfill by improper PDI (as in quarts overfilled). Foaming is why the revised service bulletin came out for the 500 mile change. Not factory overfill. That was the incorrect initial speculation.

There is no "catch can" in any C7 from the factory. A catch can catches PCV vapors from the dirty side and condenses it. Furthermore those vapors are introduced behind the throttle body into the intake manifold snout. **No way for it to go upstream in the airflow and become liquid in the intake tube. Liquid oil only comes from the sump burp line.

How do I know? I've owned both a 2014 and 2015 Z51 (and I've read almost every tech oriented post on the C7 since fall 2013). I had oil in the intake tube on my early 2014 car since it was before the 500 mile service advisory. I followed the break in, but didn't change the oil until 2200 miles and I had a quarter cup. It clearly came from the dry sump burp line since it,was collected in the pod the hose attaches to. After the oil change...zero oil for 4000 more miles and a lot harder driving. On my 2015 I followed the break in, changed the oil at 500 miles...zero oil in the intake tube...and none in the 4000 miles since.

Yes, I have a catch can on my 2015. But that's for oil vapor going into the manifold from the dirty side PCV vent in the valley..and I get about an ounce every 1000 miles.

kevincol

In the book "Corvette Stingray: The Seventh Generation of America's Sports Car" the author has Corvette product folks stating that he reason the above is necessary is that when the car is sitting, oil from the dry sump will go to the oil pan, thus showing a lower oil level. If you then put oil in while the car has been sitting, it will be too high when it is running and overflow. They have picture diagrams and everthying in that chapter explaining it. Thus I will check my oil with the directions in the manual...

Patman

Because it's such a specific method to get a good oil level reading, GM should consider adding an electronic dipstick to these cars. I've mentioned this on here before, my wife's BMW has this and I love it. You can check the level on the dash at any time once the engine has warmed up. If you overfill it, it will warn you and if you need to add oil it will warn you. Doesn't get any easier than that!

kevincol

great idea! Never had a dry sump before to ever have this "problem". I'm dealing with it, but like the BMW solution much better.

C7Joy

I just used the procedure in the book, no trouble at all. Results are repeatable.

JerryU

Here's is the why to your 1st Question: you wait 5 minutes just like you should with a typical wet sump engine, for the oil to drain down from the internals in the dry sump external oil tank. You don't wait more than 10 minutes because the oil in the dry sump tank, where you're measuring , will drain back to the oil pan over time and you'll get a low reading! (for example, after my car sat for a week I checked the oil level before I started the engine-no oil on the dip stick!) Came back from a drive, checked per the manual and it was where I left it when i changed oil, 1/2 quart low.)
2nd Question: Why I keep mine a 1/2 quart low. To get all of the oil out of the pan the scavenge pump has to pump a lot of air into the dry sump tank. That air burps out of the tank thru a hose at the top into the intake air duct after the oil filter. Along with the air, if the oil level is too high some oil and oil mist will be pulled with the air. Note a "catch can" has nothing to do with this excess oil.) For $100 you can buy a "Clean Air Oil Separator" that replaces the oil fill cap and has a 2.5 inch high container with stainless ribbon that condenses the oil mist and has in drop into the tank. (included a pic.) If the oil level is kept about 1/2 quart low less chance of oil being drawn out with the burped air. Already too long an answer, I'm sure some eyes are rolling, I discuss a "Catch Can" in a separate answer!




Clean Air Oil Separator Replaces Oil Fill Cap





Stainless Ribbon Condenses Oil Mist fro Air and it Drains Back Into Dry Sump Tank

JerryU

Is does pump in both directions but the scavenge pump that takes oil and air from the pan is a geared pump. Over time the oil does drain back. My car was parked for a week while I was out of town. Decided to see where the oil level was before I started the engine. There was no oil indicated on the dip stick! If I use the hatched area length as one quart, which it is, then it was 5 + quarts low! There is enough left to get pressure to the engine on starting and it quickly empties the pan and fills the tank. Some folks have said they hear the oil going back to the dry sump tank when the start the car that has sat overnight! Agree the oil that goes into the engine block at 30 to 40 psi is another separate pump. It's a geared pump, similar to the scavenge pump in appearance. I don't know how much drains back in 15 to 20 minutes but GM says max 10 so that is what I do.

JerryU

There are some good answers posted about "Catch Cans," but since you have an inquiring mind and want to know, I'll provide historical perspective!
Combustion products pass the piston rings and oil mist is in the crackcase. Pressure builds. This has been an issue with all cars since the Model Tee! However with the LS3 and Direct Injection it takes on much more importance! In my '50 Ford there was a simple 1 inch tube that relieved the pressure and let all that "suff" go in the atmosphere! You can see what happened to that approach to relieving the pressure and dumping the "stuff!" Manufacturers developed the PCV system (positive crackcase ventilation.) Take that "stuff" and put in back into the intake manifold and make the engine use it as fuel. Works OK except under some conditions, so a valve was added to reduce the amount when needed, hence the PCV valve! That was find but some of that oil mist and combustion products went past the hot intake valves and could bake and deposit. No problem, we'll put some cleaning agents (even more powerful than gasoline itself) into the gas and when it passes over the intake valve it will clean the "stuff" off! Worked well until direct injection (which is used in all C7's- wet and dry sump). Now no gasoline is passing over the hot intake valve, it's injected directly inside the combustion chamber. When you have big valves in a high performance engine they operate hot, this problem is worse! The oil mist bakes on the back of the valve called "coking." These carbon deposits build up and will restrict the airflow.
Enter the 'Catch Can" to help! They have been around for a while but I never considered one for my C6 with it's LT1 port injected engine. As all Vettes before the C7 gasoline passed over the intake valves and cleaned off the PCV "stuff." It is just a can (better ones have some stainless ribbon to condense oil mist) that is inserted in the PCV hose line and collects some of that "stuff" so it can be removed before it goes into the intake manifold. The next question often asked is why does GM (and others) not install one? The Catch Can must be drained periodically or it will make a bad situation worse! Folks don't even check their oil level when GM recommends and some don't change their oil when they should. Also where will they put the collected oil? I change my own oil and have a 12 quart container that I can put my "Catch Can" collected oil and "stuff' into and dispose of it properly when I change oil-many don't or won't!

360Lemans

NO!!! Hate the idea, I have a BMW 135I and can never tell the exact oil level it could be a quart over are under and the dummy dip stick light still reads the same. Also when you get your oil change from the dealer and the mechanic decides to take a short cut YOU WILL NEVER KNOW. I change my own oil and like having a dip stick to make sure its not over full, also just looking at the oil on the dip stick can give you lots of information (on the BMW you have to take the oil filter housing off to inspect the oil). I really don't understand why it's so difficult to follow and check your oil level per owners manual. I guess now a days people want Facebook to tell them how to check oil level and OnStar to tell them when oil change is needed

meyerweb

^^^^


I think the OM for every car I've ever owned says to wait a few minutes, but not too long, to check the oil. The Z51 really isn't any different. In any car, when you first turn off the engine some of the oil is clinging to parts above the pan. It takes a few minutes to drain back so you can get an accurate level. If you've been checking you other cars as soon as you shut them off, you've probably been doing it wrong.

5 minutes isn't a long time. Go grab a glass of water, have a drink, and come back.

Patman

On my wife's 2010 328i, the oil level indicator is definitely precise. When I first changed the oil I put in one quart less than I know it takes, and the reading on the dash showed that it was below the minimum and one quart needed to be added. I then added 1/4 of a quart, and the level moved up to the minimum spot, but no longer said to add one quart. I added another 1/4 of a quart and it moved into the middle of the range. Once I add the last half quart, it will then move to the maximum on the gauge and will sit there until some of the oil is consumed. I check that display every once in a while, and it will stay on the maximum for about 3 or 4000 miles and then it will move down one notch, indicating that I need to top it up slightly. I then add about 1/4 of a quart, and the level moves back to the top again. It doesn't get any more perfect than that, IMO.

I have heard other BMW owners mention that there oil level indicator does not behave like this one though, that it does not move down in small increments but only shows a different display on the screen if the oil is either way too high or way too low. But ours definitely isn't like that at all.

Porsche 911s have also had oil level indicators on their dashboard for a long time, it's an analog gauge that looks just like the fuel level. GM could easily do something like this as well. It would certainly eliminate the guesswork and allow people to have pretty much the exact amount of oil in there, no overfill and no underfill.

Al Engel

'XP800' and 'JerryU' nailed it.

Al Engel 'Save the Wave'

360Lemans

That's good, my sensor is way off but I have 65000 miles now. I just trust my own eyes and not sensors that can fault. You are correct its nice to have a read out on the dash but I wish BMW had not deleted the dipstick, both would be the perfect solution.

My post about ( I really don't understand why it's so difficult to follow and check your oil level per owners manual) was just a indirect comment about all the post I see on the forum and not directed to your post at all.

INTHERED

I really appreciate all of you taking time to respond to my questions.
I have checked my oil level several times and its about a 1/4 inch above the top of hash marks on the dipstick do you think that I should remove some oil ?
If so should I remove the oil until its centered on the hash marks on dipstick or what ?

Thanks >>>> Inthered