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Oil capacity conundrum - What the...

9K views 34 replies 11 participants last post by  yladrd61 
#1 ·
So, I did my first oil change about 300 miles ago and kept meaning to post this but kept forgetting.

Anyway, I removed the filter and let the oil cooler drain. Installed the new SRT filter.
Pulled the drain plug (car on ramps), let it drain until it was just a drip.

Put in 7 quarts of Mobil 1 0w40. All good.

However, the level on the dipstick is wonky and says that I'm about .5 quarts overfilled.

Add to that, I only got about 6 quarts out of the engine (Including filter), maybe a hair less, and before the oil change my oil level was just a hair below the top of the safe mark on the dip stick.

What gives? Do I have one of the infamous inaccurate dipsticks or is there oil hiding somewhere that I don't know about? :)
 
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#3 ·
Yes, engine was warm, everything was allowed to drain until stopped or nothing but a drip. This isn't my first oil change ever, I'm just trying to figure out if there's anything different with the 392 compared to my 5.7 in terms of oil draining. I know there have been a number of inaccurate dipsticks over the years, seemingly related to the tube not being properly or fully inserted, and the rule of thumb has been to let the engine fully drain, put in 7 quarts, run the engine, wait 5 minutes, and note the level. That level is YOUR full level, regardless of what the dipstick says.

So, I'm more curious to know if anyone else has had this happen and if there's a reason why the amount of oil I got out was so much less than the actual capacity (Factory only fills based on visual level and doesn't add a specific quantity?).

There's no way 1+ quart was lingering inside the engine after 10+ minutes of draining.
 
#5 ·
Sure, that's possible. The 392 and 5.7 are quite similar, though, since the 392 was based on the 5.7 and when I drained my 5.7 using the same ramps, same procedure, same filter, and same quantity of oil my dipstick was always spot on so while what you say is possible I haven't seen anything to suggest that is what's going on. I can't imagine where 1+ quart of oil would pool as the result of a slight incline.
 
#6 ·
I went through the exact same exercise. In the end, I drained out the excess oil until I was back to the top of the cross hatching.

I have no explanation and I posted a thread about it just like you. To date, there is no explanation that I buy. When I change the oil, I just add oil until I reach the top of the cross hatching.
 
#7 ·
Thanks, I'm not worried about being .5qt too full, just wanted to make sure that I wasn't missing anything specific to the 392. There are posts all the way back to 2011, when the 392 was first sold, where people drain the oil, replace the filter, add 7 quarts and then it shows .5qt overfilled and others commenting that the dipsticks are notoriously inaccurate and are only approximations, so it's always best to follow what the stated oil change capacity is, which is 7qt including filter, and only use the dipstick as a reference instead of using it to determine how much oil is "enough" since the engine capacity is going to be the same across all 392s, there won't be anyone that has an engine with a 6.5qt capacity and another with a 7qt, etc.

So it would seem that my "full" mark is about .5 quart over on my dipstick. :)
 
#8 ·
FYI, I always get less oil out. Between 1 to 1 1/4 quarts. I spoke to a couple of SRT techs and a few mechanics and they all said it was normal and that theses engines do burn oil. BTW, I do my oil changes the same way as you do. I don't trust the dipstick. Put in the full 7 qts. For what's worth when I did the first oil change on my brand new 15 suburban, got about 1.5 qts less out. That engine takes 8.5 quarts. Everyone says that's normal. I dunno.
So I'm assuming your dipstick I'd above the safe line, correct?


Sent from AutoGuide.com Free App
 
#9 ·
Ok, sounds like my situation is normal then. Yeah, on my dipstick the 7qts including SRT filter takes the oil level about .5qt above the upper safe line. I'd rather put in 7qts and indicate slightly overfilled than put in less just to be at the upper safe mark. It'll take more than .5 or even 1qt overfilled to cause problems and a number of folks that do racing are known to go 1qt over to ensure they don't draw air during high-G cornering.
 
#13 ·
The oil level will change based on oil temperature, dry-sump engines need to have their oil level checked with the oil up to operating temperature and right after shutting the engine off otherwise the level indicated won't be accurate.

Prime example of this is one of my Yamaha PWCs, it uses a dry-sump system with an oil tank. The level with the engine cold barely registers on the dipstick, up to temp it is perfect. The actual distance on the stick between those to levels is at least 4 inches, maybe a little more.

That's why the Challenger manual says to check the level with the engine warm and within 5 minutes of shutting the engine off. Not because it's a dry-sump engine (It's not) but because the oil level will register different depending on whether the oil is warm or cold.
 
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#14 ·
the only differences is the 6.4 has the oil cooler - with the filter off and given some time, the oil may drain out of the finned area.

My '09 always took a bit more that 7 qts to fill - I'd prefill the oil filter as well, seemed to be 7+ some additional to bring to full mark.

I'll have to see what its like when I change the oil on the SPS.
 
#16 ·
The 392 oil cooler is a cooler block mounted to the oil filter adapter on the engine block, the oil filter mounts to the oil cooler. Coolant runs through the oil cooler.
 

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#18 ·
I've always gone at my oil changes the other way around. I do everything like you did but I put in 6 quarts. Then I start it, back it off the ramps, let it idle for a bit, and turn it off and let it cool. After 10-15 minutes I check the oil on the dipstick and add more until it is at the top of the crosshatched area. I always end up using 6.5 quarts.

My logic is, if the oil capacity is actually 7 quarts, you're never going to get it all out. If you just consider the surface area that oil could still be clinging to, plus a few small nooks and crannies that a tablespoon here or a teaspoon there could pool, it could easily account for half a quart still in the engine/passages. I've always trusted the dipstick and have never assumed that "7 quarts capacity" means you should just dump in 7 quarts. To me, capacity is the total amount of oil that should be in the entire system.

But maybe that's wrong. Works for me though. :)

Mike
 
#20 ·
I've always gone at my oil changes the other way around. I do everything like you did but I put in 6 quarts. Then I start it, back it off the ramps, let it idle for a bit, and turn it off and let it cool. After 10-15 minutes I check the oil on the dipstick and add more until it is at the top of the crosshatched area. I always end up using 6.5 quarts.



My logic is, if the oil capacity is actually 7 quarts, you're never going to get it all out. If you just consider the surface area that oil could still be clinging to, plus a few small nooks and crannies that a tablespoon here or a teaspoon there could pool, it could easily account for half a quart still in the engine/passages. I've always trusted the dipstick and have never assumed that "7 quarts capacity" means you should just dump in 7 quarts. To me, capacity is the total amount of oil that should be in the entire system.



But maybe that's wrong. Works for me though. :)



Mike


I'm not worried about half a quart. It doesn't need to be exact, nothing is going to blow up by being slightly over and if I'm over by half a quart then that's just some extra cooling capacity in the oil. :)
 
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#21 ·
I was bored and curious tonight, especially after checking the level after it sat for a few hours and seeing that it looked like it was as now a quart overfilled. Yes, the safe zone height overfilled.

So, I took my vacuum evacuation tank and stuck the tube down the dipstick tube and started sucking until it was at the top of the safe zone.

When all done, I poured the oil out of the tank and into an empty 1qt bottle. What looked like 1qt overfilled ended up being only half a quart if not a little less.

So not only was it not a big deal, it was even less than I expected. It's definitely not linear as you get above the safe zone for whatever reason.
 
#23 · (Edited)
I've done 3 oil changes now and have noticed the same phenomenon as well. So on my last change I decided to sneek up on the dipstick full mark by putting in 6 Qts (dipstick showed low as you would expect) and then poured in the 7th qt, a little at a time.
What I found was that I would hit the full mark with about 12 oz left in the 7th qt. Well, I figured an extra 12 oz won't hurt anything and the dipstick shows the slight overage, but I just consider it normal.
 

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#24 ·
I don't think a half quart will matter either way (half quart low or half quart high), but it does bring up two interesting questions:

(1) Is the dipstick accurate and should that be used to determine level?

(2) When the specs say "capacity" 7 quarts... does that mean a total of 7 quarts should be in the car? Or does it mean dump in 7 quarts at each change?

I've never really thought about it and always used the dipstick. If capacity = 7 quarts means that the system should contain 7 quarts total (which is my guess), then when they build the engine and it's dry initially, they should dump in 7 quarts. After that, you will never get 7 quarts out even if the engine uses zero oil. Think about the surface area that oil travels through the engine. If you drain it, there's still going to be a film on all surfaces that it touches: oil that doesn't drain. Even if you soak a 3 foot by 3 foot sheet of aluminum in oil and then turn it vertical and wait 30 minutes for it to drain, after that if you take a squeegee to the surface, I bet you still get a half cup of oil off the sheet as oil is meant to coat surfaces and will leave a thin film.

Mike
 
#25 ·
OK just changed my oil on my Scat Pack with 950 miles.Drove up the race ramps after a 5 mile drive around town.Drained oil and went in and got lunch 20min.Still dripping one drop every 5 to 10 sec.Took the filter off Gorilla man had put it on.Filled the 041 SRT filter with oil and installed.Put 6 quarts in and drove off the ramps let run for 3 to 5 min.Shut it off and went in and had a cold one.Maybe 5 min came out and checked it .One quart down.Put the 7th quart in and that brought it up to the top fill line.All good and the oil was real dirty.Oh I also put the Magnetic Gold Plug drain plug in model MP-02.I always put a Magnetic drain plug in every car I have owned .Flat tappet cam cars are the worst for wear.
 
#26 ·
Thanks for the update. Next time I change the oil I'll let it drain a bit more, good to know that 7qts + filter was spot on for you.

If a 30-minute warm drain and putting in 7qts still shows as overfilled then I guess I can't really trust my dipstick to be honest. :)
 
#27 · (Edited)
Make sure that the dipstick goes all the way down on to the tube.I am sure you did but just be slow and push it all the way down.My full level is perfect on the dip stick.I don't know if it was a fluke but the lifter did tick at first then quieted down with the 7th quart in it.I don't know if it is true but the thing feels faster with the new oil.Maybe i just pushed the go pedal harder.LOL
 
#34 ·
There was another thread about reading the oil level on the dipstick and how it shows two different levels depending on which side of the dipstick you read (and which way you insert the dipstick). I always put the dipstick in so that the words on the top of the dipstick ring are facing me, then read the cross hatched side. If you turn it around and read the opposite side, the level is slightly different.

Mike
 
#35 ·
You should be good to go, the Dealerships have been over filling my SRT8's since 2008, I do highly recommend a catch can.
 
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