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Where does the oil from sump tank go after shutting engine off?
I am about to tackle the oil change on my 2018 GTR. The instructions are pretty clear that the remote tank must be drained within 3 minutes of shutting down the engine, after idling it for at least 30 seconds. So where does the engine oil drain to (or from where does it drain INTO the tank) after shutting the engine off? Is that other mysterious area not drainable? Just curious as I will be pumping out the oil from the tank shortly after shutting off to minimize the mess on my garage floor.
I am about to tackle the oil change on my 2018 GTR. The instructions are pretty clear that the remote tank must be drained within 3 minutes of shutting down the engine, after idling it for at least 30 seconds. So where does the engine oil drain to (or from where does it drain INTO the tank) after shutting the engine off? Is that other mysterious area not drainable? Just curious as I will be pumping out the oil from the tank shortly after shutting off to minimize the mess on my garage floor.
Yes, there are 2 drains. One from the tank and the other from the engine oil pan. Of course there is some oil accumulated in the oil filter as well.
This video should shade some more light on the process.
The oil can flow back into the engine because the oil tank level is higher.
For this reason, the oil level should be checked within 3 minutes of switching off the engine. (Always check with oil at operating temperature)
According to regulations:
When changing the oil, it is not enough to just let it run for 3 minutes. The oil should be at 100°C. The background is the oil thermostat must be open.
The oil should therefore be drained via the drain plug (filler cap closed) within 3 minutes. This generates a negative pressure through which the oil lines are then "sucked out".
Then drain the engine block oil sump. Then change the oil filter. If you do everything according to the instructions you will have to refill about 7 liters of oil.
This doesn't work when vacuuming the oil tank.
In my experience the difference is about 0.5 liters.
My opinion:
First Engine filling is 9 liters. This means: even if the oil is changed as directed, 2 liters of old oil remain in the engine.
Whether 2 or 2.5 liters remain in the engine shouldn't make a big difference.
My oil change looks like this (no claim to the best solution):
Basically I change every 5000km. (Religion? :-))
Take a good branded fully synthetic oil 0W-40 and a branded Longlive oil filter (finer white filter fleece)
personally don't care about Mercedes approval. The costs are low if you do it yourself. (here, only approx. 5% of the gasoline costs)
The motor doesn't need to be at 100 °C either. A short trip until the oil temperature reaches approx. 80°C is enough.
Vacuum oil tank. (It's simply a cleaner solution :-)) Then remove both drain plugs and let it drain completely. (I'm not concerned here with the quantity, rather with residues, and that's more for the conscience)
Remove the oil filter and visually check the slats for residue. (Also more for your conscience)
After sealing, I fill in 6 liters. Then let the engine run until the oil is at least 80° C. (It's quick since the engine is warm)
Then fill it up to the maximum level.
Info:
At nominal speed, the oil pump delivers approx. 250L/min at 4 bar.
20sec. at idle, all the oil goes through once.
The oil can flow back into the engine because the oil tank level is higher.
For this reason, the oil level should be checked within 3 minutes of switching off the engine. (Always check with oil at operating temperature)
According to regulations:
When changing the oil, it is not enough to just let it run for 3 minutes. The oil should be at 100°C. The background is the oil thermostat must be open.
The oil should therefore be drained via the drain plug (filler cap closed) within 3 minutes. This generates a negative pressure through which the oil lines are then "sucked out".
Then drain the engine block oil sump. Then change the oil filter. If you do everything according to the instructions you will have to refill about 7 liters of oil.
This doesn't work when vacuuming the oil tank.
In my experience the difference is about 0.5 liters.
My opinion:
First Engine filling is 9 liters. This means: even if the oil is changed as directed, 2 liters of old oil remain in the engine.
Whether 2 or 2.5 liters remain in the engine shouldn't make a big difference.
My oil change looks like this (no claim to the best solution):
Basically I change every 5000km. (Religion? :-))
Take a good branded fully synthetic oil 0W-40 and a branded Longlive oil filter (finer white filter fleece)
personally don't care about Mercedes approval. The costs are low if you do it yourself. (here, only approx. 5% of the gasoline costs)
The motor doesn't need to be at 100 °C either. A short trip until the oil temperature reaches approx. 80°C is enough.
Vacuum oil tank. (It's simply a cleaner solution :-)) Then remove both drain plugs and let it drain completely. (I'm not concerned here with the quantity, rather with residues, and that's more for the conscience)
Remove the oil filter and visually check the slats for residue. (Also more for your conscience)
After sealing, I fill in 6 liters. Then let the engine run until the oil is at least 80° C. (It's quick since the engine is warm)
Then fill it up to the maximum level.
Info:
At nominal speed, the oil pump delivers approx. 250L/min at 4 bar.
20sec. at idle, all the oil goes through once.
Best regards
Stenzel
This information is GOLD, as it is backed up by experience. I would rather keep some of the "old" oil and change oil more frequently vs. the mess the Mercedes process entails. I measure all fluids coming out or any of my cars and reference it for a refill. I will be using Stenzel's method on my next and periodic oil changes before my next track event. A wholehearted THANK YOU to Stenzel!
Last edited by Green_Hell; 05-15-2024 at 09:52 AM.
Reason: grammar
This information is GOLD, ... I will be using Stenzel's method on my next and periodic oil changes before my next track event. A wholehearted THANK YOU to Stenzel!
Agreed. FWIW, after each track day I consider the max oil temp reached and, based upon that (and the number of track days), optionally suck out 5+ liters of oil and refresh with new. The filter is always very clean when changed so I don't worry about that (other than yearly at <1/2 mileage interval changes), but I do want to maintain the additives in the "synthetic" oil. Somewhere I read that, at about 130 deg C (266 deg F), the oil additives start to rapidly deteriorate so I consider temps over 125 deg C vs time at those temps when deciding whether to replenish.
Agreed. FWIW, after each track day I consider the max oil temp reached and, based upon that (and the number of track days), optionally suck out 5+ liters of oil and refresh with new. The filter is always very clean when changed so I don't worry about that (other than yearly at <1/2 mileage interval changes), but I do want to maintain the additives in the "synthetic" oil. Somewhere I read that, at about 130 deg C (266 deg F), the oil additives start to rapidly deteriorate so I consider temps over 125 deg C vs time at those temps when deciding whether to replenish.
Excellent point. Not that this is critical, but I do buy my oils and consumables from FCP Euro and I am happy to report that I have used their "Lifetime Replacement" for all of my cars on oils, transmission fluids, filters, spark plugs, coil packs, brake fluid, brake pads, rotors, etc. I track my cars and I change fluids more often than most - the FCP Euro replacement policy just helps me get my butt in gear to do it. Works like a charm!
I have no affiliation to FCP Euro other than being a satisfied customer!
Is an engine assembly photo or diagram available? This would clarify the drain plug vs tank locations. 20%+ stranded oil, because of sump design, seems high.
Quick update: Vacuumed 5 liters from the tank with car warm. Took about 7 minutes. Afterwards, when I opened the tank drain, a few milliliters came out and were collected. Then I proceeded to drain the engine oil pan, drained the filter (yes, drained the filter through the hex drain plug), removed the filter. Collected an additional 1.5 liters. put everything back and refilled with exactly 6.5 liters. Drove the car, measured the oil and it was dead nuts in the middle of the dipstick. Minimum splashing or spilling and a happy motor afterwards!
05-13-2024, 01:22 PM
