One thing about this thread that is interesting to me, it seems like it if difficult to find the manufacturer’s recommended torque for oil drain plugs. I haven’t checked my Corolla’s FSM yet, but I can’t see it on AllData at all. There’s dozens of torque specs there on AllData, like for bearing caps and oil pump attachment bolts & the like, but nothing I can see for oil drain plug torque. I wonder why? Is it just b/c most everyone does it by feel?
You piqued my curiosity, so I looked into my own manual for my Toyota 4-banger, a 2AZ-FE. The spec I found is 30 ft-lbs. I cannot guarantee that it’ll be the same for your engine, but it’s something to start with.
GM seems to provide an oil plug torque value in their manuals, at least in the couple that I checked. They even gave a torque value for the oil filter, which I had never seen before.
I just did an oil change on a 2004 Chevy pickup with the 5.3L V8 that has a cast aluminum pan. I tightened the drain plug using the “snug” method. After this thread started, I looked up the torque spec in the manual (18 lb-ft). For the heck of it, today I checked the torque on the plug I had “snugged” by progressively increasing the setting on my torque wrench until I reached the setting where the plug finally budged. It turned out to be around 36 lb-ft or so–double the spec. I guess I have to ease up on my snugging. Even at 36 lb-ft, it certainly wasn’t as tight as it was when I removed it.
OK4450 brought up the issue of possible liability if a shop were to repair stripped drain plug threads using a Heli-Coil. I just discovered that many of the GM LS-series engines with aluminum pan came from the factory with some sort of thread insert (presumably some type of Heli-Coil) for the drain plug.
“Breakaway” torque is always much higher than installation torque. Many years ago as a young engineer in the manufacturing industry I had occasion to do a study on a particular application, and in that application the breakaway torque was pretty consistently about 40%-45% higher than the installation torque that was used. Different materials, thread types, thread depths, and other variables will cause the torque difference between installation torque used and breakaway torque to vary greatly by application. These numbers cannot be transferred to any other application.
Me, I’ll stick with “snug”, when using a “stubby” wrench. I think it’s the best torque spec for oil drain plugs overall.
Over the years I’ve seen a lot of stripped or generally botched up oil pan drain plugs both on steel and aluminum oil pans.
There is only one of those cases where a new pan was actually needed and there was a story behind that one.
I’ve never wrecked one either. I should add that I always use a new crush washer on the Acura.
I assume Hyundai gives the specs on my car (Sonata) because they have it posted on the forums, both for the filter and for the drain plug. I tried to go with the recommended 30 ft/lbs on the drain plug after I had used the snug/feel technique and I felt it was getting too tight. So I went with the tested method of snug and no leaks.
With a car that is new to me, for the first few oil changes I check around the plug a dat or two after the change just to get a feel for it.