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Engine Oil Change - Vacuum or Drip Method?

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Some car workshops use the vacuum method to suck out the engine oil from the dip stick hole.

 

Is this an effective method of removing sludge from the old engine oil?

 

Or is the convenntional method of allowing the engine oil to drip from the undercarriage a more effective method of removing the majority of the old engine oil?

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Some car workshops use the vacuum method to suck out the engine oil from the dip stick hole.

 

Is this an effective method of removing sludge from the old engine oil?

 

Or is the convenntional method of allowing the engine oil to drip from the undercarriage a more effective method of removing the majority of the old engine oil?

 

Neither. Both are just ways to remove old oil and no matter which method you use, some oil will still be left in the engine. Bo pian wans.

 

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Some car workshops use the vacuum method to suck out the engine oil from the dip stick hole.

 

Is this an effective method of removing sludge from the old engine oil?

 

Or is the convenntional method of allowing the engine oil to drip from the undercarriage a more effective method of removing the majority of the old engine oil?

 

Metal fines and oxidation particulate-emulsion (acidic) settle in the oil sump (the lowest point of the engine).

 

Vacuuming the oil upward will not drain these completely and which will continue to erode your cylinder internals, piston rings etc, even after you replace with new oil.

 

Draining from the bottom will rid of most of these first by gravity-stratification (though there may still be some left, due to wall-effect), but not as signficant to erode your engine internals after new oil has been replaced ..... basically fines/particulates depleted.

 

I had boycotted one 'famous' Merc workshop, after I saw them vacuuming oil from the top, on my previous Merc. Totally unprofessional.

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Most of the vacuum oil extractor operated by compressed air and the vaccum created is the highest possible - that is 25" of mercury. Draining by gravity flow is slow, time consuming and it's definetly an obsolete way of removing engine oil. It is a slow process and most of the mech hate to do such job.

Which way is more efficient - to vacuum the floor/carpet or to use a broom to sweep?

Most of the car owners find very difficult to accept oil change via vaccum extractor , it's due to the mindset and most of the workshop just fail to explain the concept correctly.

The reason why most shops are very inefficient and very low in productivity , it' also mainly due to continue use of out of date workshop practice and the unwillingness to explore new and innovative idea.

 

Photo show a simple oil extractor being used on vehicle, Machinery etc

post-272-1262606139_thumb.jpg

Edited by Yeobh

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I hear some workshop use compress air to aid the expel of used oil from the drain plug. Maybe they blow it thru the oil cap or dip stick tube?

 

My prefer method is use around 1 litre of fresh oil, pour it into the fill cap and flush out those remaining used oil. Can be wasteful but the oil coming out from the drain plug is very much cleaner, and new oil stay cleaner much longer.

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Vacuum suction will save time and hassle. Many new cars have hard to access drain nut under the car, some have to remove the undertray just to access the nut. Also to use the bottom method the car have to be raised up and there is potential for the hot oil to splash onto skin or worst the eye.

 

Unless the manufacturer has design the dip stick slot to end at the lowest point in the engine oil sump, if not the vacuum mehod might not suck up all the waste oil in the sump.

 

Vacuum system has more pro than con.

1. Save time

2. Save labour and effort

3. Save changing drain nut + seal

3. Save jacking up danger, avoid oil spill on workers

 

 

 

 

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If the compressed air volume is high and only partial volume escape via the drain plug opening the remaining air may cause damage to the crankshaft end oil seals.

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Many european cars dip stick opening have even built in with a quick air coupler to take the vacuum oil extractor suction tube connector. The Dip stick opening has a built in tube that goes right to the lowest part of the soil sump.

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my regular ws uses the airgun to blow into the engine til no more dripping of the old oil, then pour the new oil. the dipstick shows shiny new oil.

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I hope the mech is not breathing in all the oil mist laden air. The boss looks like having a poor understanding of good workshop practice/housekeeping -very bad for the enviroment and the staff working in the shop

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Actually the best draining is to leave your car overnight in the workshop and get it drain first thing in the morning. all oil would have flow to the sump at least 95-98%. You are kidding yourself when you think while the engine is hot, either vaccum or normal draining will drain 100%, no way.

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If the compressed air volume is high and only partial volume escape via the drain plug opening the remaining air may cause damage to the crankshaft end oil seals.

 

Now that you've mentioned oil seal, I remember something....

 

The construction of oil seal the cross section is something like a "C". The 'concave' side is suppose to be at oil side where there is some pressure, 'convex' side is outside, atmosphere side. Most oil seal the internal concave side got spring to help it seal tight against the shaft, and the fluid pressure also helps it to act inside the concave side where by helping oil seal to seal better.

Of course the lip of the oil seal plays an important part by keeping the fluid at the inside on a rotating shaft, but that's another design feature....

 

So going by the theory on how oil seal works, blowing compress air would be much safer than vacuum inside the crankcase. Oil seal would leak easier if there is vacuum inside the engine internal than pressure, right?

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Check with your workshop, make sure they have blanket insurance coverage in case there is a fire.Many decades ago there was such case where three cars were in that shop. That night a fire broke out and destroyed all the three cars. All the car owners were not able to claim compensation against the shop as the boss operated without any such insurance.

Also which shop want to do oil drain that allow you to occupy the car lift for the whole evening right up to tomorrow morning as the mech maybe be doing some overtime work for some rush job.

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Actually the best draining is to leave your car overnight in the workshop and get it drain first thing in the morning. all oil would have flow to the sump at least 95-98%. You are kidding yourself when you think while the engine is hot, either vaccum or normal draining will drain 100%, no way.

 

 

U r correct but how many car owners will actually leave their car in the workshop overnite? :huh: Anyway.. i have tried the conventional way of draining engine oil & vacuuming... from my personal observation, after using the vacuum method, my car was able to take in more new engine oil than thru the conventional draining thru the drainage hole. So mayb thru vacuuming, more oil can b "drained" out & in fact more thorough of removing old oil. But this is my personal opinion & observations lah. :ph34r:

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I hope the mech is not breathing in all the oil mist laden air. The boss looks like having a poor understanding of good workshop practice/housekeeping -very bad for the enviroment and the staff working in the shop

 

act its jus norm airgun blowing into the engine, it jus helps to "push" all the oil out, not sure how it will mist the air...thanks bro.

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The vaccum is only at the small opening ( 1/4") of the tube and is about 6" from both end of the crankshaft. I mention high volume workshop compressed air ( about 120psi) - which is very dangerous if apply at the wrong place.

 

PS This incident happen in the early 70's ,one service station pump attendent place an compressed air gun at the back of another worker. The compressed air enter the anus and cause serious damage resulting in death.

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Official factory oil change is done by draining.

Thats the reason why cars are made with the drip hole.

contrary to (poor knowledge) belief, there is no need to drain until so dry.

Once the dripping stops, it is good enough

 

Kiang ok, mai keh kiang.

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My regular workshop raised my vehicle up on carlift, and drain the oil via the engine sump drain hole.

I think this is sufficient, as the drain hole is supposed to be the lowest point, and sediment would follow the engine oil down.

While the oil is draining, they will carry out some quick check of undercarriage.

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