I'm pretty sure the technical title is "Little Dipstick Tube"...
April 23, 2006 11:01 AM   Subscribe

Well, here's a dumb one: can I pour motor oil down the, uh, little tube where my dipstick rests?

The quite-surprisingly-complicated oil cap on my engine broke last night when I was about to put in half-a-quart of oil. Don't worry, it's still on there nice and secure, and nothing fell into the engine or anything. It was actually the housing of the cap--it had springs in it!--not the cap itself.

So I'm going to need a wrench and at least an hour of profanity and wrench-throwing before that cap comes out. In a pinch, can I just use a funnel, and slowly pour some oil down there?

If it matters: Crown Victoria, 1996, totally sweet.
posted by Ian A.T. to Travel & Transportation (13 answers total)
Sure. That's how you add transmission fluid - through the appropriate dipstick tube... Pour slowly. Slowly! Being a half-quart low isn't going to to kill your engine anyway though, so you can just wait until you've beaten the main oil cap if you wish. (Try to get some WD-40 into the cap threads to help solve that problem.)
posted by jellicle at 11:19 AM on April 23, 2006

Funnel. Don't forget the funnel.
posted by sgobbare at 11:37 AM on April 23, 2006

Does the dipstick always go directly into the oil pan? I imagine that it could be possible to have some kind of secondary reservoir that might help clean up the measurement under some circumstance. If that were the case, you would have to pour extra super slow in January, or something..
posted by Chuckles at 12:00 PM on April 23, 2006

You should buy a 710 cap. They cost a bit more, but they're worth it.
posted by weapons-grade pandemonium at 12:22 PM on April 23, 2006

Chuckles: The dipstick goes into the oil pan. There's no need for a reservoir, since the engine oil level should be checked when the engine is not running (thus, the oil isn't flying all over the place inside).
posted by peewee at 12:38 PM on April 23, 2006

Use a funnel and go slow.

One of the problems is that, as you add oil, air's going to have to come out. Depending on how you busted your oil cap, you might have an airtight system if you block the dipstick hole with incoming oil.

So don't be too surprised if air bubbles up through the dipstick tube, splashing oil everywhere.
posted by ikkyu2 at 1:52 PM on April 23, 2006

Yeah, go very slowly with this approach. I had to do it once and ended up with a mini ecological disaster.
posted by falconred at 2:31 PM on April 23, 2006

Yes. Many boats (which are powered by car engines like yours) do not have have an accessible oil drain plug, so instead the oil is sucked trough the dipstick tube.
posted by vaportrail at 2:36 PM on April 23, 2006

The top of the dipstick tube is often fairly grubby, so you'll probably want to wipe it up fairly carefully before stuffing the funnel in there. You don't want to push or wash crap into your motor.
posted by flabdablet at 5:07 PM on April 23, 2006

If you run a small-diameter tube down through the funnel, into the airspace above the oil in the crankcase, you won't get bubbling back through the descending oil. To clarify (I hope), the tube should be long enough to stick up out of the funnel, with the lower end below the bottom of the dipstick tube. Air displaced by the oil you're adding will come back up through the small tube.
posted by Kirth Gerson at 6:06 PM on April 23, 2006

If you do this, I would avoid the pouring method, it simply is too tricky at this scale. I have had good luck moving viscous solutions like this around (80% glycerol in water, eg) with a large (~50mL) syringe and various bores of tubing. If you loaded a regular PE syringe with tubing (honestly, I am not sure where you get these in the real world, we order them from places like here for lab use.) If I decant/funnel I make a mess, if I pipet I make a mess and it takes all day.

With that said, it sounds like in the time it took you to get a hold of something like this, you may have the oil cap thing taken care of, so maybe mating decreasing diameters of tubing to the bottom of a funnel until you have one small enough to go in the hole? I just know that spilled oil smoke for the first few tens of miles is nasty.
posted by oxonium at 6:10 PM on April 23, 2006

If you loaded a regular PE syringe with tubing (honestly, I am not sure where you get these in the real world, we order them from places like here for lab use.)

And I got distracted midsentence again, should read:

If you load a regular PE syringe with tubing it should work fine. (Honestly, I am not sure where you get these in the real world, we order them from places like here for lab use.)

posted by oxonium at 6:12 PM on April 23, 2006

Response by poster: Thanks everybody! I cleaned out the dipstick tube, used a very thin funnel, went really slowly, and everything was fine.

I was 99.5% sure that this was okay--I'm not quite as mechanically disinclined as my post would suggest--but I wanted at least one person to second me before I did it.

(If there were ever a car with a "dipstick oil reservoir" or some other reason that would make pouring oil in there a Very Bad Idea, it's a Ford. They're the Microsoft of cars!)

In a few days, when this drops off the first few pages of the site, I'll mark almost everyone's answer as Best. Thanks again!
posted by Ian A.T. at 9:11 PM on April 23, 2006

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