Sponsored

Checking the Oil

TomcatDriver

Well-Known Member
Joined
Mar 8, 2017
Threads
9
Messages
1,159
Reaction score
469
Location
Mojave Desert
Vehicle(s)
2017 GT350 Magnetic w/black stripes
I know this topic has been covered more than once, but rather than resurrecting some very old thread that doesn't quite match I started a new one. I've checked the oil in my GT350 pretty religiously at least once a week or so, usually on weekends or fill-ups. I don't wait for drain-back on fill-ups but it's always been in the hashed region. Last time I checked it hot with about a 20 minute drain-back it was about the middle of the hashes. I checked it cold yesterday and it was below the hashes. This concerned and confused me since I had not driven it much since my previous hot-check. I added about 3/4 quart to near the top of the hashes then drove it a while. First quick check (hot, no drainback) and it was above the top of the hashes. After sitting 15 minutes, went and checked again and it was still above the hashes.

So, why would it indicate that much lower cold than hot? Was I hallucinating the low cold reading?
Sponsored

 

JAJ

Well-Known Member
Joined
Apr 9, 2016
Threads
4
Messages
1,984
Reaction score
1,687
Location
Vancouver BC
Vehicle(s)
2016 GT350 Track Pack
Oil expands when it's heated, and unless the engine and oil pan also expand, you'll get higher readings hot than cold.

The upper "full" mark is actually the hole above the hashes, so if you're still below that then you're not over-filled.
 

MrCincinnati

Well-Known Member
Joined
Jun 20, 2017
Threads
24
Messages
895
Reaction score
473
Location
Cincinnati
Vehicle(s)
2017 GT350R
I know this topic has been covered more than once, but rather than resurrecting some very old thread that doesn't quite match I started a new one. I've checked the oil in my GT350 pretty religiously at least once a week or so, usually on weekends or fill-ups. I don't wait for drain-back on fill-ups but it's always been in the hashed region. Last time I checked it hot with about a 20 minute drain-back it was about the middle of the hashes. I checked it cold yesterday and it was below the hashes. This concerned and confused me since I had not driven it much since my previous hot-check. I added about 3/4 quart to near the top of the hashes then drove it a while. First quick check (hot, no drainback) and it was above the top of the hashes. After sitting 15 minutes, went and checked again and it was still above the hashes.

So, why would it indicate that much lower cold than hot? Was I hallucinating the low cold reading?
What the other guy said about hot vs cold. Be careful with consistency when checking the oil. I try to always check it in the same location (same spot at my home) to ensure consistent readings. Also per manual and as you’ve now discovered - wait 15min before checking.

A quick check when cold to make sure you’re not running dry is fine - but you should not add oil based on cold check unless the stick is actually dry.

It gets kinda old checking it all the time in this manner but it also prevents you from overfilling or running low.
 

DCShelby

Well-Known Member
Joined
Jan 24, 2019
Threads
17
Messages
1,131
Reaction score
839
Location
DC
First Name
Robert
Vehicle(s)
2018 GT350 Lighting Blue and 2017 Ducati 1299S
I did an experiment once with mine. Checked when hot but did it right after shutdown and then 5 minute intervals till I reached 15 minutes. It definitely showed a level difference at the start and then end.
 
OP
OP
TomcatDriver

TomcatDriver

Well-Known Member
Joined
Mar 8, 2017
Threads
9
Messages
1,159
Reaction score
469
Location
Mojave Desert
Vehicle(s)
2017 GT350 Magnetic w/black stripes
What the other guy said about hot vs cold. Be careful with consistency when checking the oil. I try to always check it in the same location (same spot at my home) to ensure consistent readings. Also per manual and as you’ve now discovered - wait 15min before checking.

A quick check when cold to make sure you’re not running dry is fine - but you should not add oil based on cold check unless the stick is actually dry.

It gets kinda old checking it all the time in this manner but it also prevents you from overfilling or running low.
I knew what the manual said before this, and that's what I usually do. The usual problem is to be consistent with the drain back time. If you check immediately after turning the car off every car I have ever owned is going to read a little bit lower than after you let it sit for a few minutes, but usually you will get a bit of a high reading if you let it sit longer as more oil drains out of the engine into the pan (which is more than the thermal expansion). I've been checking oil in cars for a long time, and I have never seen that much difference between hot and cold. I'll let it settle overnight and see what it says in the morning just for reference.
 

Sponsored

OP
OP
TomcatDriver

TomcatDriver

Well-Known Member
Joined
Mar 8, 2017
Threads
9
Messages
1,159
Reaction score
469
Location
Mojave Desert
Vehicle(s)
2017 GT350 Magnetic w/black stripes
I did an experiment once with mine. Checked when hot but did it right after shutdown and then 5 minute intervals till I reached 15 minutes. It definitely showed a level difference at the start and then end.
Higher or lower? That is, did it go up every 5 minutes as more oil drained into the pan, or go down every 5 minutes as the oil cooled?
 

DCShelby

Well-Known Member
Joined
Jan 24, 2019
Threads
17
Messages
1,131
Reaction score
839
Location
DC
First Name
Robert
Vehicle(s)
2018 GT350 Lighting Blue and 2017 Ducati 1299S
It goes up as the oil drains back in the pan. Note the oil is hot and it takes quite a while to cool off 10 quarts of it. If I was really anal I’d get it hot, then check it every 5 minutes till it cooled so much the level goes down. That might take a few hours but being a geek engineer I suppose it would be interesting to record. To be super anal you could do this test at various ambient temperatures. Or I might just go drive it or take the Ducati out.
 

MrCincinnati

Well-Known Member
Joined
Jun 20, 2017
Threads
24
Messages
895
Reaction score
473
Location
Cincinnati
Vehicle(s)
2017 GT350R
I knew what the manual said before this, and that's what I usually do. The usual problem is to be consistent with the drain back time. If you check immediately after turning the car off every car I have ever owned is going to read a little bit lower than after you let it sit for a few minutes, but usually you will get a bit of a high reading if you let it sit longer as more oil drains out of the engine into the pan (which is more than the thermal expansion). I've been checking oil in cars for a long time, and I have never seen that much difference between hot and cold. I'll let it settle overnight and see what it says in the morning just for reference.
I agree with the abnormal procedure for something so routine with this vehicle. I think that may be a reason why so many people are being caught out with starvation etc. For the most part the people buying these vehicles have checked the oil in a car before and prior common experiences lend to a different result set than experienced with this car. And even after reading the manual - unless you’ve been on a forum like this where owners like myself are standing up shouting CHECK YOUR OIL! Then the manual directions may even seem like a bit of CYA.. but that 15min window is critical for accuracy and owners of this vehicle are finding out the hard way what happens when it’s ignored.

After 21k miles I’m now at the point where I feel I know when I’m burning oil and when I’m not (driving style) so my oil check habits follow my driving behavior.. meanwhile I may have checked the oil on my 70k mi 392 charger twice in 70k mi between changes.
 

OnTrack

Active Member
Joined
Dec 16, 2018
Threads
1
Messages
39
Reaction score
18
Location
Fort Worth Texas
First Name
Patrick
Vehicle(s)
2018 GT350 Ruby Red
Check the oil at the same exact time interval to ensure you have a consistent reading. I check mine at the 15 minute mark each time which gives me the consistent reading for fill up. I have not had to add any oil yet despite my driving style, but haven't started hitting the track fully yet. My Z06 was the same procedure on waiting 20 minutes for drain and needs to be considered vs immediately. ,
 

GT_Dave

Well-Known Member
Joined
Dec 13, 2015
Threads
11
Messages
1,075
Reaction score
688
Location
NE Illinois
Vehicle(s)
1970 Mach 1 408EFI , 2016 GT350
I knew what the manual said before this, and that's what I usually do. The usual problem is to be consistent with the drain back time. If you check immediately after turning the car off every car I have ever owned is going to read a little bit lower than after you let it sit for a few minutes, but usually you will get a bit of a high reading if you let it sit longer as more oil drains out of the engine into the pan (which is more than the thermal expansion). I've been checking oil in cars for a long time, and I have never seen that much difference between hot and cold. I'll let it settle overnight and see what it says in the morning just for reference.
The 10 quart capacity in the GT350 makes a significant difference for the expansion factor, more so if you compare the change to cars with 5 or 6 quart capacities. Something you need to consider checking hot compared to cold.
 

Sponsored

JAJ

Well-Known Member
Joined
Apr 9, 2016
Threads
4
Messages
1,984
Reaction score
1,687
Location
Vancouver BC
Vehicle(s)
2016 GT350 Track Pack
It's easy to over-think this issue. If the oil is anywhere on the hash marks when you check it, regardless of hot or cold or however long it's drained, then you're fine. If it's below the hash marks, add a half-quart.

All of the factors discussed above might make a 1/4" difference in the reading, but that doesn't matter if it's not overfilled or underfilled. Hence the "add a half-quart" solution. That won't be enough to overfill it if it isn't needed, and it'll get it into range if it is.

The only time you can't check it is when it's running.
 

Hack

Well-Known Member
Joined
Nov 26, 2014
Threads
83
Messages
12,283
Reaction score
7,444
Location
Minneapolis
Vehicle(s)
Mustang, Camaro
I always check my oil when the car is dead cold. I think it eliminates the time factor as a variable. Plus, I prefer not to work on a vehicle when it's hot.

I always had very consistent oil level readings doing it that way. The oil level was pretty much always mid-way between the dots.
 

galaxy

Well-Known Member
Joined
Feb 16, 2018
Threads
232
Messages
3,224
Reaction score
2,533
Location
St Louis
Vehicle(s)
'17 GT350
All of the factors discussed above might make a 1/4" difference in the reading, .
And to put it in perspective what JAJ said, keep in mind you're debating ounces. Literally (almost) single digit ounces between hot and cold readings. In a 2.5 gallon system. Let that sink in.

I always check my oil when the car is dead cold. I think it eliminates the time factor as a variable. Plus, I prefer not to work on a vehicle when it's hot.

I always had very consistent oil level readings doing it that way. The oil level was pretty much always mid-way between the dots.
The owners manual is the owners manual right, but consistency is all that really matters. THIS works.
Sponsored

 
 




Top