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Old 03-21-2009, 02:46 PM   #1
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Oil guage lies?

Ok, so I took the Boxster to a local oil place and they drained it and put in 9.25 quarts of Mobil 0W40 and the dip stick say's it's at max but the electronic guage says it's over filled. It's conceivable that the oil dude didn't let it fully drain...

What's the deal and who/what do I trust?

Any insight is appreciated.

-Steve

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Old 03-21-2009, 03:03 PM   #2
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Very likely the drain time was insufficient, especially at a quick lube place.

If you have a mity-vac, get some tubing and extract about a half qt. from the dipstick tube, or raise the car and remove the filter cover, that'll yield about a qt. Save it in a clean container and add some back as needed over the next few days.

But, remember, Porsche revised it's recommended fill capacity but never revised the dipstick or the dash gauge.

Previously, you were to fill to the max line on the dipstick and to the bar below the top bar on the dash gauge.

With the revision, you now fill slightly over the max line on the stick (it's a guess how much, maybe 1/4") and to the top bar on the digi-gauge... there is no more overfill indicator.
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Old 03-21-2009, 03:15 PM   #3
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Hmmm... so if that's true and the guage says over the max I'm ok???

Thanks,
-Steve
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Old 03-21-2009, 03:59 PM   #4
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Quote:
Originally Posted by chitowndad
Hmmm... so if that's true and the guage says over the max I'm ok???

Thanks,
-Steve
Not necessarily, see by eliminating the overfill indicator, you have no way of knowing if you're overfilled or not, and because of this, I personally feel it's better to keep the digi-gauge at 1 bar below and the dipstick slightly over the max line as I'd said. Trust the dipstick over than the dash gauge - use the digi-gauge only for convenience at startup.

For those w/o dipsticks, 1 bar (about 8 fl. oz.) below the top is still in the OK range, and OK is OK - better than risking an overfill.
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Old 03-21-2009, 04:05 PM   #5
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What happens if you overfill?

-SP
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Old 03-21-2009, 07:49 PM   #6
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Quote:
Originally Posted by chitowndad
What happens if you overfill?

-SP
If you overfill the oil 'foams' meaning that it cannot flow to the crank and rod bearings or the the cams... VERY BAD!!
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Old 03-22-2009, 02:14 PM   #7
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Overfilling can also cause high crankcase pressure, which in my opinion, is a likely cause of RMS leaks. I've seen this on BMW motorcycles more than once. (I wrench on motorcycles for a living, and also have a degree in physics... really I do)
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Old 03-22-2009, 05:58 PM   #8
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Don't forget that the digital dipstick is only accurate when the car has been sitting 30+ minutes on a level surface with the motor off.
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Old 03-22-2009, 06:07 PM   #9
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It looks like the TSB that Increased the oil fill amount was issued in 2/99. I assume this means owners of 2000+ cars should follow the fill levels of the gauge and dipstick.
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Old 03-22-2009, 06:30 PM   #10
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I'm pretty sure it's overfilled... I need to find the mini vac and pull some of the oil out through the dip stick. The oil guys only let the car drain for like 5 minutes! The weird thing is that when I check the oil right away it's good but when it sits overnight it's too high! UGH! And now my jack isn't lifting the car high enough to push some stands under it to drop the oil filter. Grrr. I'm so frustrated with the oil pro guys!

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Old 03-22-2009, 07:07 PM   #11
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Quote:
Originally Posted by chitowndad
I'm pretty sure it's overfilled... I need to find the mini vac and pull some of the oil out through the dip stick. The oil guys only let the car drain for like 5 minutes! The weird thing is that when I check the oil right away it's good but when it sits overnight it's too high! UGH! And now my jack isn't lifting the car high enough to push some stands under it to drop the oil filter. Grrr. I'm so frustrated with the oil pro guys!

-Steve
It takes some time for the oil to drain back into the sump. The meter and dipstick are meant to be read on a cold engine.
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Old 03-22-2009, 08:13 PM   #12
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Quote:
Originally Posted by blue2000s
It looks like the TSB that Increased the oil fill amount was issued in 2/99. I assume this means owners of 2000+ cars should follow the fill levels of the gauge and dipstick.
That may not be so safe an assumption. The Part #'s for dipstick and oil level sensor, filter, sump, etc. have not changed, been superceded or made MY specific.

To me, this means that none of the oil capacity measuring devices have been recalibrated to the new standard. My local Service Manager agreed when we spoke about it.

Either way, following the 'old' standard isn't likely to prematurely kill a street car because it will leave you in the OK range.
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Old 03-23-2009, 07:26 AM   #13
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Quote:
Originally Posted by Lil bastard
That may not be so safe an assumption. The Part #'s for dipstick and oil level sensor, filter, sump, etc. have not changed, been superceded or made MY specific.

To me, this means that none of the oil capacity measuring devices have been recalibrated to the new standard. My local Service Manager agreed when we spoke about it.

Either way, following the 'old' standard isn't likely to prematurely kill a street car because it will leave you in the OK range.
The 2003 owners manual still says to not allow the oil level to drop below the min mark or rise above the max mark on the dipstick.
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Old 03-23-2009, 07:44 AM   #14
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Quote:
Originally Posted by blue2000s
The 2003 owners manual still says to not allow the oil level to drop below the min mark or rise above the max mark on the dipstick.
Well, that seems to be an incongruity between the manual, the TSB and the PET which does NOT denote a change to the dipstick PN# (which Porscher does in every other known upgrade or supercession) through all the model years that use dipsticks... it's the same dipstick (PN# 996.107.014.02)... same calibrations.

I would suspect that in the face of this evidence, that the owners manual is incorrect.

It says the exact same thing in my '99 owners manual:
"The Oil level must in no case fall below the minimum or exceed the maximum oil level on the dipstick..." Now we know this has to be incorrect in my manual (at least) due to the TSB revision. And, if they haven't recalibrated the dipstick in subsequent years (and there's NO indication that they have), it must be incorrect in later manuals as well.

I suspect that in subsequent owners manuals, it's just a carryover from previous ones. They do not re-write the entire manual every year, probably only revise it where applicable. It's easy to see this as an ovesight.

No matter though since that notation in the manual will keep you in the OK range. The difference between the MIN/MAX marks represents 1.6 Qts., so there's plenty of cushion there.

But it only stands to reason that if you add an additional amount of oil (as directed in the TSB) that the level will show higher on the dipstick, unless the dipstick has been recalibrated to reflect the added oil, which it apparently has not.

I guess the point is to not obsess about keeping it FULL because of the risk of overfilling, just aim for the upper end of the OK range.
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Last edited by Lil bastard; 03-23-2009 at 08:05 AM.
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Old 03-23-2009, 07:56 AM   #15
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Quote:
Originally Posted by roadracer311
Overfilling can also cause high crankcase pressure, which in my opinion, is a likely cause of RMS leaks. I've seen this on BMW motorcycles more than once. (I wrench on motorcycles for a living, and also have a degree in physics... really I do)
Also cause of AOS failures.
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Old 03-23-2009, 08:10 AM   #16
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Ouch! Overfilling with oil can kill the AOS pretty quick.
I use Econolube for annual oil changes but not without a Porsche inservice seminar with the service tech first. I assume they no nothing about a Porsche.
1. I supply the oil, filter, crush ring and specialty tools .
2. Drain for 20 minutes warm.
3. Required torque settings.
4. Fill with 8.5 qts only, I will top off tomorrow.
$20 bucks

I prefer this method to doing it myself in the garage and then disposing of the used oil later.
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Old 03-23-2009, 09:13 AM   #17
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Originally Posted by Topless
Ouch! Overfilling with oil can kill the AOS pretty quick.
I use Econolube for annual oil changes but not without a Porsche inservice seminar with the service tech first. I assume they no nothing about a Porsche.
1. I supply the oil, filter, crush ring and specialty tools .
2. Drain for 20 minutes warm.
3. Required torque settings.
4. Fill with 8.5 qts only, I will top off tomorrow.
$20 bucks

I prefer this method to doing it myself in the garage and then disposing of the used oil later.
Disposing of used oil is free.
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Old 03-23-2009, 12:59 PM   #18
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Quote:
Originally Posted by blue2000s
Disposing of used oil is free.
Overstating the obvious?
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Old 03-23-2009, 08:59 PM   #19
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OK... let's say this happens to someone either by their own doing or by a 3rd party accident.

What is the best way to remove the excess oil?

Let's also assume you don't want to go back to the 3rd party that made the mistake.
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Old 03-23-2009, 10:30 PM   #20
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Quote:
Originally Posted by funkdefino
OK... let's say this happens to someone either by their own doing or by a 3rd party accident.

What is the best way to remove the excess oil?

Let's also assume you don't want to go back to the 3rd party that made the mistake.
See my 1st post to this thread.... ↕


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