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Discussion Starter · #1 ·
I use RP duralec 15w40. The previous change I overfilled when refilling, just pouring in 5 quarts without thinking. Drove a few hundred miles before realizing it. Didn't seem to affect anything - no foaming - and pressure was somewhat higher so left it. Seems to make the valvetrain a little quieter....maybe. it goes up to the first bend on the stick.

To my warped thinking the extra oil might allow for lower oil temp., more volume of oil = less dirty oil. No change in coolant temp. MAYBE a little lower mpg but I'm sorta due for plugs anyway.

Fast forward 6k miles and I'm at my next change (I know low miles for synthetic) so I'm thinking doing it again since I'm not seeing any problems. Other than that, no changes in the car despite 1k highway miles a month going on it.
 

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93 NA ATX 3000gt DOHC
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Fast forward 6k miles and I'm at my next change (I know low miles for synthetic) so I'm thinking doing it again since I'm not seeing any problems. Other than that, no changes in the car despite 1k highway miles a month going on it.
I wouldn’t recommend running it overfull, even though you didn’t notice foaming on dipstick, crank hitting liquid oil surface or disturbing it with windage from crank rotation will foam oil. That foaming will increase with length of drive and/or RPM’s, gradually inducing air into complete oil volume and pump will then be circulating the air infused oil to bearings and etc.. This has been known to cause engine failures.

It’s been confirmed manufactures dipstick high level mark is near bottom of crank, maybe for extra volume safety or engine/oil cooling as you suggest. But foaming on especially long drives or higher RPM's is more dangerous in my opinion (I know every body’s got one). What I do know from experience it will lower fuel mileage and horsepower. Dyno test have shown even at proper oil level, simple windage from crank at higher RPM’s increasing horsepower at certain RPM’s the monitored oil pressure started to drop off. In those test, because of aerated oil reaching the pump it lost it's ability to properly pressurize the oil, as stepped amounts of oil was removed below full mark, each dyno pull showed more horsepower and less oil pressure drop at higher RPM's. Of course there’s a point you must stop removing oil before oil starvation will occur because most of oil will be in upper portions of engine, that’s why dry sump oil systems are often used in racing engines.

Sorry if I bored you or anybody else with this long text.:p
 

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Discussion Starter · #4 ·
@white93gt is most likely right. Here is a 3sx writeup on our oil pans and where the "full" mark lines up to the pan: Tech - Oil Pan Capacity Test. How Much Oil Is REALLY In The Oil Pan. | 3SX Performance Home Page

Basically there isn't a whole lot of space there. If you look at the 4th picture down the 1st bend above the "full" mark is basically the bottom of the girdle.
Hold on there a second, the labels on the pan they're using says that at the full mark on the dipstick, it's at 3.5 quarts. There's not possible way that's right. Unless they're using the "fill the filter with a quart of oil" which won't work either because my filters won't hold anywhere near a quart.

My overfilled oil level is right at the 3" mark on the ruler in this photo so I'm pretty sure I'm once more worrying about nothing.


With 3 quarts in the oil pan, the level is exactly at the height of the splash plate around the deep / pickup side of the oil pan. This also means you are essentially at the "low" indicator on the oil dip stick. Meaning when the oil is at the "low" mark on the dip stick, there is actually 3 quarts of oil still sitting in the pan - and that's not including oil that is in the rest of the engine / oil filter / oil cooler lines / etc.
Adding another half quart brought the capacity up to 3.5 quarts hits the "full" indicator on the oil dip stick. So when your oil dip stick is reading "full" that means you have about 3.5 quarts of oil actually in the pan.
 

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My overfilled oil level is right at the 3" mark on the ruler in this photo so I'm pretty sure I'm once more worrying about nothing.
I too wonder about the 3.5 quarts statement, I believe it’s more like ~ 4 quarts in pan and ~ ½ quart in filter.

BUT …… If you look carefully at picture you can see crankshaft counter weight flange barely above full notch under crank main bearing girdle. Which means with your overfill on ruler 3” mark the crank is already in top portion of oil. We both know when engine starts some oil will be pumped up into upper parts of engine lowering oil level in pan a little, hopefully the engineers knew that too and that crank windage would be reduce a little. But with you running the level ~ 3/8” above full, you’re increasing the aeration of the oil because of the increased crank windage.

Although dipstick oil level was not covered in dyno test runs showing the oil pressure drop from aerated oil at upper rpm’s, the about of oil removed was in the 1 ½ quart range from full (IIRC) which would put oil level on 3S dipstick below the low level mark and near bottom tip most likely. :unsure:

This is best info I can supply, but I do understand, your engine your call and your diving conditions/habits might not mean you have reason to even consider this. :unsure:
 

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Panama Green,mostly stock with 13G's, Oohnoo SMIC, money pit
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I remember as a kid right before a long trip on the interstate the old man grabbing a can of oil and punching a hole in the steel top of the can with the steel filler nozzle with its point on it- hey any of you young guys have a clue what I am talking about?



Anyway , he always said to add a about 1/2 to 1 quart extra for those long trips. Hmm, well that was on the old Impala with its 283 and powerglide. I seem to remember that most times at the 3rd fill up we had to add a quart.... We have come a long way since then. no more round quart cardboard oil cans...

I would think that on this car with that baffle the oil level is best just below the baffle in the pan.

P
 

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I remember as a kid right before a long trip on the interstate the old man grabbing a can of oil and punching a hole in the steel top of the can with the steel filler nozzle with its point
Hey ...... who you calling an old man? :unsure: ..... I used that type of oil spout many times....... Hmmm... well must admit .... I am an old man. :)
 

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Discussion Starter · #8 ·
I too wonder about the 3.5 quarts statement, I believe it’s more like ~ 4 quarts in pan and ~ ½ quart in filter.

BUT …… If you look carefully at picture you can see crankshaft counter weight flange barely above full notch under crank main bearing girdle. Which means with your overfill on ruler 3” mark the crank is already in top portion of oil. We both know when engine starts some oil will be pumped up into upper parts of engine lowering oil level in pan a little, hopefully the engineers knew that too and that crank windage would be reduce a little. But with you running the level ~ 3/8” above full, you’re increasing the aeration of the oil because of the increased crank windage.

Although dipstick oil level was not covered in dyno test runs showing the oil pressure drop from aerated oil at upper rpm’s, the about of oil removed was in the 1 ½ quart range from full (IIRC) which would put oil level on 3S dipstick below the low level mark and near bottom tip most likely. :unsure:

This is best info I can supply, but I do understand, your engine your call and your diving conditions/habits might not mean you have reason to even consider this. :unsure:
I've never red lined my car and probably never will to be honest.

The 3.5 quarts makes no sense - they're missing a full quart of oil somewhere. The filter is way to small to account for it. Which reminds me, I still haven't gotten an answer as to whether or not the oil cooler drains with the crankcase. If it doesn't, that's a lot of dirty oil sitting around. Anyways......

To add the strangeness of this, my oil pressure is slightly higher with the extra oil. I am too suspicious of the photos in the article to take them at face value or very seriously.

I can't imagine that the full mark on the dipstick would be that close to the crankshaft so that sudden stops, hard cornering would slosh the oil onto the crank. Granted the photos show a baffle in the oil pan but it still defies logic that the stock level is that close to the crank unless I'm totally misinterpreting the information.
 
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