How do I find the specified torque for the drain plug for the oil pan on my car? This information is not in the owner’s manual or the service manual (which I have).
This is for a 1988 Chevrolet Nova (comparable to a Toyota Corolla). The plug specs are: M12 x 1.25mm.
Choke up on the wrench and tighten as much as you can.
There isn’t one, because it’s not known if the drain plug is being removed/reinstalled with the engine hot or cold. Such as at a quick-lube place.
And because the threads in the oil pan are coated with oil, it has to be a wet torque spec.
So, the drain plug is tightened by feel.
Tester
Torque spec for a Toyota drain plug with the aluminium washer is usually between 28-30 ft-lb.
I use a “stubby wrench”. Done so for 45++ years. I’ve never stripped a plug or lost one.
A “stubby” limits the amount of torque you can apply, and while everyone’s strength is different, and every vehicle is different, 45++ years of success cannot be denied. I was, after all, young and strong once. 
Power to the stubbies!
there is snug, tight and overtightend, snug to tight, sure it is a matter of feel, wonder if my oil change guys use a torque wrench.
I don’t see that spec in the torque spec data I normally use either. I see values on the internet in the 25 ft-lb range for the Corolla in general, matching up with Nevada’s estimate above. I don’t see anything though for your specific make/model, which I presume is Corolla derived.
Consider that the manufacturer has a conflict of interest for this spec. They’d rather error on the side of too tight than too loose. After all, loss of engine oil is a much worse problem to deal with compared to having to fix the threads in the oil pan or drain plug or replace the oil pan. I’m a diy’er and have changed the oil in my driveway for my cars for years. For my own Corolla, just a few years newer than yours, I can tell you how I do it, never had a problem damaging the threads on the drain plug or oil pan.
First off – I think this is very important to prevent thread damage and leaks – I always use a new gasket. When tightening the oil drain plug I use a 12 inch handle ratchet/socket and hold it with one hand about 6 inches from the plug and tighten it just so it starts to snug up, then another 1/8 of a turn. I’d guess about 15-20 foot pounds.
I usually buy my drain plug gaskets at Toyota, in a batch of 10. If I discover no washers are left in the middle of an oil change, I don’t drive to Toyota in the other car to buy some new ones. Instead --now I’m not recommending this mind you – I’ll make my own appropriately sized gasket from 3 mm thick neoprene gasket material I keep on hand.
And I carefully clean the area off, then visually check for leaks from the oil filter and drain plug after doing an oil change, both at idle rpm then at higher rpms.
I would recommend that you take it easy on the drain plug. About 12 foot pounds should do it.
I give it a good tug after being tight. On my Acura, I had to use a 12" pipe over the 3/8 ratchet to get the dang thing loose. So that was more than “tight”.
I have a standing rule: I use a bigger than necessary wrench to remove things and a smaller wrench to install them. If torque is critical, I use a torque wrench. Torque specs don’t work well for drain plugs for the reasons already mentioned, so good sense is a critical tool too.
I recently had one come in that was so tight and the lands rounded off that I almost didn’t get it out. I finally had to carefully grind new lands into the head and that did the trick.
The local dealership told the owner they would need a new oil pan.
I’m sure it won’t be the last one to come into my shop like this.
Like most have mentioned…use the shortest wrench and you won’t over tighten it.
Yosemite
I use the following spec: snug
That’s the same spec I use; snug.
Perfectly defined: snug.
Yosemite, I get upset whenever I hear of a dealership telling someone they need a new oil pan because of a drain plug problem. I’d never heard of that until a year or two ago, and suddenly I’m hearing of it almost on a routine basis. Just last year a dealer shop changed a friend/neighbor’s oil pan because his threads were stripped… and the dealer that did this is the only shop that has ever worked on his car, including oil changes. He himself hasn’t; he’s too disabled to even try. He bought the car new from them in 2012 and has always taken it there only. They charged him $500 or $600, I forgot exactly. I was pissed. He was pissed too, but his wife had told them to go ahead.
IF a dealer told a customer that the threads could be easily and inexpensively repaired for whatever the shop would charge and that they had the option of having the pan replaced for hundreds of dollars and the customer opted for a new pan, I wouldn’t be bothered at all, but that isn’t what seems to be going on. I believe shops are ripping people off. 
I do not agree with the policy (if that’s the case…) of recommending an oil pan replacement simply because of failed threads in the bung.
None of the places I’ve ever worked did this thank God.
Playing Devil’s Advocate for a moment I might pose a few things about a full pan change.
One is the obvious make work/additional profit part of it.
Two could be this. What if a shop installed an oversized plug, Heli-Coil, or whatever and there was a problem later with the plug falling out. The engine was ruined or another shop botched an oil change later on a repaired pan and laid the blame on the shop that did the repair?
It’s possible that the word could spread to other shops and could have made them all once bitten, twice shy.
Third could be the trend towards younger tech school guys coming into the workplace and replacing the entire pan simply because they don’t know any better. Installing a Heli-Coil may come across as frightening machine work to them and they may fear the plug coming out followed by loss of employment…
In case the OP would prefer an actual number to ‘snug’, that same part number drain plug used in a later Geo Prizm (successor to the '85-'88 Nova) has a torque spec of 26 lb-ft according to the Prizm service manual. That jibes closely with Nevada_545’s numbers.
One problem with using torque is that quite often the person doing the torquing has no idea of the condition of the threads.
Someone might apply 16 Ft. Lbs and pull every thread in it.
I have only had my oil changed 5 times in my life. Twice on an 8600 mile trip ( one loose drain plug and one loose oil filter and over filled the engine ). Once when it was cold out and a local muffler shop had a $9.95 oil change special. ( I was amazed he could so overtighten the drain plug with the vise-grip he chewed it up with).
The last two were free from the dealer along with tire rotations. The oil changes were ok but they way overtorqued the lug nuts every time.
Some pans are steel, some aluminum. Some drain holes are deep with lots of threads, some are shallow with fewer threads. Some cars have plugs that were replaced and the threads may not be as efficient as the original plug threads.
I’ve done literally hundreds of oil changes. I’ve had cars with all of the above descriptions.
I snug my drain plugs by hold the ratchet with my palm over the ratchet head, not by the handle. I have stubby ratchets, but they aren’t really needed for this if you don’t use any length of the handle for leverage.
I’ve never had a plug loosen up or leak and every time they come out with a little bit of effort, but not excessive force.
Easy does it. A drain plug looks like a bolt, but it is not a fastener. It is a plug used to retain fluid.
CSA
OK4450, I personally like your third theory. Lack of knowledge/machine tool exposure.
Your other point about not knowing the preexisting condition of the threads is always a danger. I’ve changed oil on vehicles not my own where I’ve almost needed a breaker bar to get the plug out. Scares the bejeezeus out of me. That’s why nobody touches my drain plug but me. I think lack of proper training is a factor in these cases as well… and in some cases perhaps lack of integrity.