Oil change
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Burning Brakes
Joined: Nov 2002
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From: Ohio
Oil change
I change the oil in all my cars. In my C5 it called for 7.5 quarts. After a while I just put in all 8 thinking no foul no harm. Never caused an issue. My C8 calls for 7.5 quarts. Will 8 quarts cause any issues or damage. The extra 8 oz should not make a difference…will it?
Popular Reply
Dec 2, 2023, 07:34 AM
Race Director
Joined: Aug 2019
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From: Central Illinois
I've changed the oil in my C8 SR three times and it takes 8 quarts to be exactly at the top of the cross hatch while the car is at operating temp, on level ground, and idling. As long as you also change the filter (can't imagine not) it actually takes 8 quarts. BTW, the idiot that wants to overfill can cause damage to an engine, an engine without a dry sump has an oil pan and the last thing you want to do is swing a crankshaft through oil. If the engine is healthy, it won't use any significant amount of oil between changes so there is absolutely no reason to overfill.
Safety Car
Joined: Mar 2010
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From: Wickenburg, Az
Did you fill the new oil filter before putting it in place before adding the 8 qts? If not that would be the dif. If you are on the crosshatched area of the dipstick at idle and eng. temp at 175 degrees than all is ok.
Drifting
Joined: Oct 2018
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From: C&D 10 Best loop
I had a neighbor who always added an extra quart of oil to his truck, saying “they underfill ‘em so they wear out faster and you buy another one sooner.” Added extra oil to his riding mower as well. Wouldn’t surprise me if he even took a swig of it during oil changes.
Don’t be that guy. Fill it to the specified level and save any extra oil for the next change.
Don’t be that guy. Fill it to the specified level and save any extra oil for the next change.
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I have found that on the C5s that I had and now the C7, if I put in just what the owner’s manual recommends, it registers just where it should be on the dipstick. I do not put in any extra.
Race Director
Joined: Aug 2019
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From: Central Illinois
I've changed the oil in my C8 SR three times and it takes 8 quarts to be exactly at the top of the cross hatch while the car is at operating temp, on level ground, and idling. As long as you also change the filter (can't imagine not) it actually takes 8 quarts. BTW, the idiot that wants to overfill can cause damage to an engine, an engine without a dry sump has an oil pan and the last thing you want to do is swing a crankshaft through oil. If the engine is healthy, it won't use any significant amount of oil between changes so there is absolutely no reason to overfill.
Race Director
Joined: Mar 2007
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I change the oil in all my cars. In my C5 it called for 7.5 quarts. After a while I just put in all 8 thinking no foul no harm. Never caused an issue. My C8 calls for 7.5 quarts. Will 8 quarts cause any issues or damage. The extra 8 oz should not make a difference…will it?
There is a "centrifugal air/oil separator" near the top of the oil tank - its considered part of the crankcase ventilation system - and a tube vents the separated vapor from the tank back to both rocker arm covers. If the tank is overfilled then oil might start to pass through that line, instead of just vapor. I'm not sure what the exact consequence of that would be - but would expect it to have a detrimental effect on the crankcase ventilation system.
Burning Brakes
Joined: Feb 2013
Posts: 904
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From: Sacramento, California
I've done 2 oil changes on my 23. The 1st time I added 7.5 quarts and never checked the oil level, but when I did the 2nd one I checked the oil level after the engine was fully warmed up and found I was low on the stick. After adding 1/2 more quart the level was still in the cross hatched area just below full. 7.5 quarts gets you to the minimum and 8 quarts gets you closer to the full mark.
Race Director
Joined: Sep 2016
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7.5 quarts fills mine to the halfway point in the cross-hatched area. 8 quarts to the very top of the cross hatch. No, 8 quarts won't hurt anything. With a dry sump system, even overfilling it by half a quart (8.5 quarts) isn't going to hurt anything.
The real answer is to fill it to the right level, not by volume. As long as you're between the middle of the cross hatch and the top you'll be fine, whether that's 7.5 or 8 quarts.
The real answer is to fill it to the right level, not by volume. As long as you're between the middle of the cross hatch and the top you'll be fine, whether that's 7.5 or 8 quarts.
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Drifting
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I've changed the oil in my C8 SR three times and it takes 8 quarts to be exactly at the top of the cross hatch while the car is at operating temp, on level ground, and idling. As long as you also change the filter (can't imagine not) it actually takes 8 quarts. BTW, the idiot that wants to overfill can cause damage to an engine, an engine without a dry sump has an oil pan and the last thing you want to do is swing a crankshaft through oil. If the engine is healthy, it won't use any significant amount of oil between changes so there is absolutely no reason to overfill.
Instructor
Joined: Nov 2015
Posts: 198
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From: Dallas, TX
I did my first oil change today and with 7.5 quart, it was right in the middle of the crossmark area. 8 will be at the top and that is fine. I believe the manual want to fill up to middle area, not to the top of the crossmark.
Race Director
Joined: Aug 2019
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From: Central Illinois
For 100 years you put oil in to the top of the range markings, you don't ever exceed it, you just put it to the full mark. If half way is what GM intended, then they should have had the top hatch mark be where the oil level is 7.5 quarts. The middle gives you virtually no reference as to whether or not it has used some oil or not. Sorry, but that makes no sense at all, much less when you look at a dipstick and say "she's a quart low", anyone that has said that adds to the top mark.
Racer
Joined: Feb 2017
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From: powder springs georgia
oil change
I have a 2022 htc vette and have the oil changed 2 times so far by dealer...Since they use quarts and not a drum of oil I asked If i could have any leftover oil...I picked up the car with about half a quart of oil included. They charged me for 8 quarts.To me they fill too much..Mine was right at the very full mark, both times. I took out about 8 oz. so the stick is at about 7/8 within the top hash mark.
I think in mine 7 quarts would be perfect but 7.5 puts it at very full .....All measurements taken at right temp. with motor running..
I think in mine 7 quarts would be perfect but 7.5 puts it at very full .....All measurements taken at right temp. with motor running..
Race Director
Joined: Mar 2007
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I would be filling mine to the top of the hatched area (when warm) and have no concern about that. The manual is clear that it can be anywhere in that hatched area. There is still ample space above the level of the oil when at the top of the hatched area, and the air/oil separator and vent tube at the top of the tank. See post 6, which illustrates the position of the dipstick .
This system, obviously, is different from designs with a oil filled sump. The level in the tank has nothing to do with how much oil the engine parts receive - all of that is pumped from the tank to and through the engine, then scavenged from the sump and engine valley and returned to the tank. So, the only concern about the oil level in the tank is 1) too full such that oil starts to flow back through the vent tube to the rocker arm covers, or 2) too low such that that there is no oil to pump to the engine. I believe that if the oil is anywhere in the hatched area, there is ample protection from either situation.
This system, obviously, is different from designs with a oil filled sump. The level in the tank has nothing to do with how much oil the engine parts receive - all of that is pumped from the tank to and through the engine, then scavenged from the sump and engine valley and returned to the tank. So, the only concern about the oil level in the tank is 1) too full such that oil starts to flow back through the vent tube to the rocker arm covers, or 2) too low such that that there is no oil to pump to the engine. I believe that if the oil is anywhere in the hatched area, there is ample protection from either situation.
Race Director
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Just the same, I would not be running it near the lower end of the hatch area. An old habit I suppose, based on older technology and excessive caution. It provides some margin if the car should use some oil. Technically the manual says add oil if "If the oil is below the cross-hatched area at the tip of the dipstick, add 1 L (1 qt)". In other words, strictly interpreted one could run it at the low mark. I would never do that. My point previously was just that the level in the tank, anywhere between the hatch marks, does not affect engine lubrication at all - which differs from an oil filled sump. But there are other reasons I prefer to keep the level in the tank closer to the higher end of the hatched area.
Race Director
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From: Central Illinois
Race Director
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I think some don't understand how a dry sump system works. The oil is drawn in from the dry sump tank, not the oil pan. 7 quarts is still well above the oil pickup. Since there's no oil sitting in the crankcase, overfilling by a little bit can't cause oil frothing or foaming. The only draw back to running at 7 quarts is that contaminants don't get diluted as much, and if the car is being driven really, really hard, the oil might run a ittle hotter. I like to fill mine to the top of the crosshatch, just before, but halfway, or even the bottom isn't going to hurt anything.
Le Mans Master
Joined: Apr 2006
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From: Goodyear Arizona
I change the oil in all my cars. In my C5 it called for 7.5 quarts. After a while I just put in all 8 thinking no foul no harm. Never caused an issue. My C8 calls for 7.5 quarts. Will 8 quarts cause any issues or damage. The extra 8 oz should not make a difference…will it?
Safety Car
Joined: Mar 2010
Posts: 3,612
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From: Wickenburg, Az
I think some don't understand how a dry sump system works. The oil is drawn in from the dry sump tank, not the oil pan. 7 quarts is still well above the oil pickup. Since there's no oil sitting in the crankcase, overfilling by a little bit can't cause oil frothing or foaming. The only draw back to running at 7 quarts is that contaminants don't get diluted as much, and if the car is being driven really, really hard, the oil might run a ittle hotter. I like to fill mine to the top of the crosshatch, just before, but halfway, or even the bottom isn't going to hurt anything.
True, every 911 dry sump discussion on any 911 site recommended half way up the cross hatched area and not 'full' up...for a dif reason ( Full up old 911's tend to suck oil into the intake) but that is perfectly safe and correct.