Oil Drain Plug

Why can’t I get Walmart guys to change my Kia Sedona engine oil? They say the plug is cross threaded and they don’t have a spare. The dealer says they aren’t well trained and that nothing is wrong with the drain plug; when the engine is hot, the aluminum oil pan expands and holds the plug. Am I stuck with using the dealer for oil changes or do I have a problem they are hiding?

change the oil yourself when the motor is cold.

It could be that changing the oil in your vehicle is very difficult ( I don’t know) and Wal Mart does not want to change it. Take that as a clue and don’t ask them again. If that is true I would have more respect for them if they said something like “it’s very difficult and we respectfully turn down the job” instead of making something up.

How would the pan getting hot and expanding (getting bigger) hold the drain plug tighter? Isnt the abilty of the drainplug to accept torque what hold it in? Some cars do have damaged drain plugs (or more correctly the threads in the pan are damaged) We used to suck the oil out the dipstick tube if we felt there was going to be a issue upon removal of the plug.

Anytime you thread disimular metals together, heat them up and cool them back down, and then try unthread it, it can gawl the softer threaded material. The oil pan.


Youdidn’t say if the dealer removed and reinstalled the plug and the oil or not, so other than “saying” there is nothing wrong with how does he know.

It may be just policy at WM not to attempt an oil change on cars with Al pans, (as they may have a history themselves of stripping and x-threading, it’s a very common problem. Like some stores will not change tyres on Alloy wheels.)

otherwise, change it yourself. Just don’t overtighten the plug.

“when the engine is hot, the aluminum oil pan expands and holds the plug”

Not quite right. Even in High School physics we learned that the hole expands at the same rate as the plate material (change-in-size per change-in-temperature). So, unless the plug material’s coefficient of expansion were greater than or equal to the pan’s, the plug would actually get looser as it got hot. Wikipedia’s article on Coefficient of Expansion gives 29 for aluminum. Other metals that might be used for the plug range from about 11 (iron and various steels; bad choice to use with aluminum for saltwater corrosion) to 17 (stainless steel; OK with aluminum for corrosion) to 19 for brass. Nevertheless, if the plug really did tighten up when things heat up, that sounds like a bad design. I would be suspicious of the dealer’s claim. (“What! How can you say that?!?!”)

I would trust Tester’s knowledge that potential galling is a problem with disimilar metals, but that, too, sounds like maybe a design flaw. Could the plug be aluminum???

If WalMart does not feel competent to do the job, you should be happy they refused it (see A Murphy’s comment). That’s better than having some overconfident yahoo mess it up. Perhaps that is an indication that you should avoid Quicky Chain on this one, at least until you get the true info. (Contrary to the expert advice here, I do use Jiffy Lube for oil changes – but I watch them like a hawk, and I do not let them sell me their extra services.) If you do not want to change the oil yourself (I have done it, and it’s a bigger pain/inconvenience for many of us than it is for the experts on this site), then try to find an independent mechanic. Maybe you’ll find somebody who can take care of you car better and cheaper than the dealer.

First if Walmart or anyone does not want to work on your car, your don’t want them working on your car.

I am a little suspicious of the dealer’s comments. Have they been servicing the car? Did they see the car? Normally I would not recommend getting oil changes or regular maintenance at a dealer, they just charge too much and don’t do a better job. In this case I suggest checking the Mechanix files on this site or asking your friends and neighbors to find a local INDEPENDENT mechanic and have them check it and do the oil change.

Try this site for a new drain plug. Install it once and you never have to remove it.


So if you take the car on a long trip and the engine (oil pan) gets really hot . . . it expands so much that the oil plug will fall out? Crapola! Do it yourself when the engine is cold. Period. Rocketman

That thing there would be a trick on a diesel truck, the only thing is, I wish it was made a little better as is, I’d be afraid of it.

The bail isn’t or doesn’t appear to be locked down. Otherwords, it appears I could run through a pasture or some such and have grass or vines or limbs accidentally flip the bail over and there’d go my oil and then my engine. Alternatively, it’d be easy for some kid to crawl under it at Wal Mart or some such and flip the bail. You’d come out to a heck of a mess under your truck with 3 or 4 gallons of oil running everywhere.

What would make that better IMO is if they had a keeper of sorts that screwed down over the flange and locked the bail in the closed position and you needed a wrench to loosen it so the bail could be opened and the oil drained.

It’s main advantage to me would be the ability to fill up jugs instead of pouring over 3 gallons of oil into a pan and then having to deal with that mess.


“Crapola,” you say? I just did the math. For a steel plug (alpha = 11 ppm/deg-K) exactly fit into an aluminum hole (alpha = 23), the DIFFERENCE in the diameters will be 10% of the original diameter if the temperature rises by 8,333 deg-K = 14,999 deg-F. So the plug WILL fall out … because the oil pan will have melted :>)

Nonetheless, I doubt that heating the pan/plug would make the plug TIGHTER.

There’s gonna be a BIG line for new motors for KIA owners . . just imagine all of those owners who drive their cars on a long trip to the beach . . . only to find that the oil plug has fallen out! I respect your calculations and theory, but I stilol think it is crapola. Rocketman

Right. The piece expands “photographically”, exactly like blowing up a photograph. The hole gets bigger too. The dealer service rep is, as usual, full of bovine organics.

If the plug is the only part cross threaded, the hole should be “chased” with a tap and a new plug installed. If the hole is (also) stripped, it shoudl be tapped oversize and an oversize plug installed.

The hole holds the plug in when the material expands? Where DO these service reps get their cockamamie ideas?

There is a slight difference in the expansion coefficient between Al and steel, but it’s not enough to explain the plug not coming out. I always change my oil how to get more of it to drain, but you can do it either way without much effect.

Regarding the OP, there are other choices besides the dealer and walmart. Find a good independent shop and use them for your work, including oil changes if you don’t want to do them yourself.

Yep, thats one very handy little gadget.

For the past thirty yars the way that I have changed oil is to drive my car or truck up on my ramps, flip the lever on the fumotovalve & R&R the oil filter by hand.

Oil changes don’t get any quicker or simpler than this.

And while it’s up on the ramps I can take a quick look for any early signs of leaks/torn CV boots etc.

It seems that service departments at some dealerships will say almost anything. I had requested that the Ford dealer change the oil in an Aerostar that I owned at the time. The service writer came back with a long face and told me that the drain plug had been overtightened and that they couldn’t get it out. I produced the record that showed that the dealer was the last place that had changed the oil. I told the that “you put the plug in, so you figure out how to get it out”. I insisted that they give me a ride home and take care of the problem which they did. I also never went back to the dealer for oil changes.

I’m not certain how WalMart detected that the oil drain plug was cross threaded if they didn’t remove it. Could it be that the head on the plug was rounded by a careless technician?

Skip, i’ve used Fumotovalves for over a million miles on my & my wifes various cars & trucks. Never a problem.

The only time I mess with the drain plug is the first oil change on a new car or truck. The drain plug comes out & the Fumotovalve goes in.

The lever is spring loaded & has to be pushed up & over to drain. This isnt going to happen from running thru rush.

wow! Thanks all 18 of you for your wonderful input. I printed the collection of responses and will get the dealer service manager’s opinion on what his folks told me.