Engine oil removal through diptube and others....

[Deltona]

Why?

A few newish European cars now have no sump plug and the oil is sucked out of the dip tube when changing it, I can't think of a more stupid idea, but there must be a reason for it, anyone any ideas?*

I like to look at how things are done on new cars when I get chance (incase there are things to be learned and applied to my own older car), but I just can't get my head around some of the weird things I see sometimes - I had a look at the intake manifold that was removed from a VW turbo diesel, the inlet was at one end, it ran along, did a U-turn, back the other way, another U-turn then went into the plenum, but why? Why make the air go further and round more flow losing U-bends? Noise reduction perhaps?

*It would be too easy to say it is to thwart any keen DIYers as hardly any 'normal' people get their hands dirty these days and for those that want to the tools to do the job are readily available....

Any additions or answers appreaciated.

 

[GregLocock]

I'd guess a sump plug costs around $3, and will cause a small but discernable number of oil leaks, and within the warranty life of the vehicle sucking oil out of the dipstick is acceptable.

So far as the manifold goes, all sorts of reasons are possible, noise is quite likely the main one.



Cheers

Greg Locock

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[Peter7307]

I suspect cost is the main factor as Greg stated above but ham fisted mechanics stripping the thread in an alloy sump will also be a consideration.
Had this happen with my car at an authorised dealership !

By the way this is not a new idea...I first saw it advertised at a national franchise car wash and vacuum clean distributorship in the late 1970's.

The idea being anyone who knew where the dipstick was could carry out an oil change.
Never tried it myself.

Pete.

 

[BigVlad]

Probably there is no sump plug for same reason automatic gearboxes don't usually have sump plugs - it can't come loose if there isn't one. Car engines in boats have been having their oil changed by sucking it out for years.

 

[franzh]

Many dipstick tubes do not extend to the bottom of the sump, leaving a considerable amount of oil remaining. I took a look at my 5.0L Ford engine sitting on my stand and the tube is a full two inches from the bottom of the sump. On a good day, it MIGHT vacuum the top inch, or about one quart of oil.

Franz

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[Lou Scannon]

Well, at least the cost of changing your oil would be lower!

 

[romke]

cost was not the object to introduce engines without drainplug. the idea is to make maintenace easier - you don't have to crawl under the car to get to the drain plug, and the hot oil does not run up your sleeve when you get it out.

mercedes was the first manufacturer to introduce it way back in the 80-ties(after thorough testing), together with an oilfilter that was easily accessible from under the hood.

they took care to position the dipstick guide in such a way that the (rather wide) suction pipe reached the lowest part of the oil pan so only a minimal amount of oil remains in the engine when sucked empty this way. they also stipulated the use of only a view types of suction apparatus that are compatible with their design. basically these have a metal suction pipe and they work better then apparatus with a plastic pipe that may deform under the heat still in the engine.

 

[BrianPetersen]

A lot of new cars (particularly European, but probably others as well) have a plastic belly-pan underneath the engine, mostly for aerodynamic reasons, although it helps with keeping debris and dirt and direct water splash/spray out of the engine compartment, too. If you use a drain plug, the belly pan has to come off, typically with a lot of screws (my VW diesel is like this). It's less labour to suck it out from the top, and a lot of people do this with the VW diesels ... although I prefer to do it the old way, if nothing else but to have an excuse to look around underneath for signs of other fluid leaks, cracked CV boots, and the like. VW still puts a drain plug there.

I don't know why they don't just put a small access hole in the belly pan to allow the drain plug to be reached without taking the whole belly pan off. I've thought about doing that myself, but every time I'm doing an oil change I can't be bothered, so it's never gotten done.

 

[patprimmer]

Some late 80s onward Hondas and Toyotas had a plastic underbelly under the engine compartment. It had to be removed to change oil. After ten or so years of removal and replacement, the attachment points become so damaged that they cannot be refitted. An access hole for oil change would certainly improve that, however I expect the manufacturer has little interest in improving durability beyond 10 years.

Regards
Pat
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[ivymike]

as mentioned above, they've had aftermarket kits for this for decades. If you've got a good shot to the bottom of the pan, I don't see the harm in it. That's how I draw oil samples for analysis.

If it really torques you off, then drop the pan, weld on a plate, drill and tap the plate, and install a removeable plug.

 

[RossABQ]

Personally I always like the kits that put a lockable ball valve in place of the drain plug.

I'd hate to suck steaming hot oil out of a car that just drove in (a la Jiffy Lube).

 

[ivymike]

If it helps, I don't think they use their mouths for the task.

My neighbor has one of those lockable quick-drain plugs. The odd thing is that the only position it locks in is "open." It's held closed by friction, gravity, a whole lot of luck, and a very small spring.

 

[Deltona]

Thanks very much for your thoughts gents, the plastic undertray is my favourite reason so far.
It has been suggested elsewhere that this could have been done for health & safety reasons, not only the danger of splashing hot oil, but also its potentially carcinogenic properties. However, it has to be said that any proper mechanic over the age of 13 should be able to drain the sump of oil without bathing in it, not only through experience and having the correct tools, but also from having some decent degree of manual dexterity.....

 

[TurboXS]

In the 1980's a number of UK Petrol Stations had a "change your own oil through the dipstick service." The sales pitch was a "clean and easy way of changing your oil".

 

[romke]

that service was introduced in more european countries at that time, with little succes. both due to the public not really wanting it and the fact that they used all kinds of small diametre plastic tubing to suck the oil out - which did not work well with many cars, especially not when the oil was relatively cold.

nowadays the system is only used in workshops servicing cars and vans that are expresly designed to have the oil changed that way.

 

[drwebb]

It would only take a small hole in the belly pan for drain plug access, but a bigger one for the filter (or top access) which presumably would affect the aero benefit of the pan proportionally. Several interesting explanations here- may be a combination of all (including declining DIY oil changes in the market, especially under warranty) . . .

 

[Peter7307]

Another thought is perhaps fewer back yard mechanics changing their own oil means more of it will end up at recycling stations and not be disposed of improperly.

Pete.

 

[oldfieldguy]

This not an uncommon way of changing oil with many small fixed marine engines. The apparatus to perform this is available ready-made. I have personally used two different ones on two different engines.

The kits I've used had a relatively stiff plastic pick-up tube of diameter small enough to slide inside the dipstick tube of the engine in question, even though the engine had the standard dipstick tube of around a quarter of an inch (6mm) ID. Sliding the stiff pickup tube into the dipstick tube gave a better access to oil in the bottom of the oil pan.

The small diameter of the pickup tube made the oil change a bit slow if the oil was cold, but we all know that oil should be changed hot anyway.



old field guy

 

[SomptingGuy]

Honest question...

How does all that lovely sediment in the sump get sucked up?

- Steve

 

[jasongreat1]

I would be afraid of a ball valve. When I was working on a drill rig we installed a ball valvle to make changing the oil easier. What we didnt account for was the extra vibration because of the weight of the ball valve. About half way through the week the nipple going to the valve broke and we lost all the oil, if it wasnt for the operator watching the gauges so close we would have lost the motor. Granted it was a huge cummins with alot more vibration but I wouldnt trust it on my car, surely not if all I had was a dummy light for oil pressure.
As far as the funny shape of the intake I would venture to guess it would be to increase the available air charge to help the torque of the motor down low and let it breathe easier at high speeds. Like a common single plane intake versus a dual plane intake. Just my .02 cents.