Oil plug loosens

What in the world would make my oil plug loosen on its own. I would say 4 out of the last 6 oil changes had it barely hand tight. And no, I didn’t miss tightening it after changing the oil. I use a torque wrench to 35 lbs (5 more than specified). I have 2 torque wrenches and they are calibrated. I use an OEM plug and new crush washer every time. Fortunately there isn’t even 1 drop of oil around the plug before changing. Today while rotating tires I just checked the plug from an oil change 3 weeks ago. I bet it was 20lbs. I tightened it back to 35. Any clue?

 

Fumoto. One and done, never worry about it again ever.

 

Some frown on this, but put a little Teflon tape on it. Don't wrap it out to the end of the stud, you don't want any getting into the system.
I've always done this because it helps with a little more of an interference fit.
It's also been my experience that it helps keep the front diff fill plug from seizing so damned tight.

 

AND, you can back the plug out a little, wrap some around it and run it back down.

 

Crush washer? Or the oem blue sticky metal washer? (maybe it's the same thing)

 

If you bought the blue drainplug washers off Amazon, that can happen. (or any aftermarket blue type)
Been a few guys have this issue with them.

If you do a search here on TW, you'll find a few threads on this happening.

 

I have had this exact thing happen to me. So I decided to start by getting a new drain plug. I go to the dealer and get one. While Im there I get a couple of new oil filters and the guy at the parts counter throws in a few crush washers. Get home to change the drain plug and noticed that the OEM crush washers that I had were different than the OEM crush washers I got from the dealer. I put the new crush washer I got from the dealer with the old drain plug, tightened it up and didnt have a problem with it loosening up. I do remember that the old crush washers I had were bought off Ebay awhile back and I might have got some knock off Toyota washers.

 

It's possible your oil pan threads have been jacked over time if the plug was over torqued or cross threaded, especially if it's been getting loose the last several oil changes.

 

Are you sure the old crush washer got removed? Done 37 oil changes on my 07... never had a loose plug. I only hand tighten... never use a torque wrench on it. Have read a few stripped oil pan threads here... not sure if it's aluminum but i treat it like it is. Maybe try some blue loctite?

 

The plug I put in 3 weeks ago is a pricy machined one with a magnet. The package of crush washers was from Amazon and is suppose to be OEM but we know that isn’t always true. I always feel for a stuck crush washer when wiping the pan clean. I also make sure I find the old one in the dirty oil or around the plug. I have used a torque wrench to 30lbs and don’t think I’ve ever over tightened it. It does have 206K miles so that’s 41 oil changes so maybe on the worn threads.

Thanks for the ideas. I’m just going to check it every few weeks and see how it goes. I’ll probably get a package of crush washers from the dealer.

 

this all day.

 

Why would a fumoto stay in while a normal plug loosens? Do you use lock tight on it?

 

Fumoto drain plugs are a "set it and forget it" as you only need to install it once and use the valve to drain your oil. No more dealing with drain plugs and gaskets. Plus Fumoto offers varieties were you can even angle the drain/hose in different directions so you can direct the flow and still not drip a drop of oil.

 

My 2011 does the same thing. It is never loose enough to turn by hand, but a wrench breaks it free with hardly any effort. I use the OE washer with the blue material and change it every time. I never used a torque wrench on the drain plug, and maybe I've over-torqued it in the fear of not having it tight enough and partly stripped the pan threads. I replaced the plug and it does the same thing. I've thought of using one of the oil pan bolts as an anchor, drilling the head and safety wiring the drain plug, but instead I put a long piece of Gorilla Tape over the plug after changing the oil. The tape stays stuck to the pan, and even if the plug were to loosen it can't back out. I have a habit of looking under my truck for puddles before I get in it in the carport and have never yet seen one, so I guess I'm good to go.

 

The counterfeit blue toyota washers are the most bizarre thing that I've seen counterfeitted, but that is worth checking.

I want to say the real ones are a soft almost fuzzy blue, whereas the fake ones are a shiny plasticky blue.

But really the outside of it is not the concern right? It needs to be made of the right kind of metal that will crush on tightening to help keep the threads of the drain plug tensioned.

 

I stripped my transmission drain plug by torquing to spec. I learned the hard way that torque specs are normally given for dry, unlubricated threads. Wet or lubricated threads materially reduce the torque required. I knew the plug was stripped because next time I went to change the transmission oil the plug was hand tight. Since then I don't use a torque wrench on wet threads.

Let's assume that your torque wrench is accurate, and for wet threads you should use 75% of the dry torque spec. (This 75% is an estimate and there could be a wide range here).

Dry torque of 30 x 0.75 = 22.5 for wet torque (again 75% is an estimate). Your torque setting of 35 (5 above 30 standard) is 56 % above 22.5. Hopefully the threads on the drain pan aren't damaged, but there shouldn't be a need to over tighten a drain plug to stop it coming loose. I have a 2010 too, with 44 oil changes, no issue with the original drain pan or original drain plug (hand tightened snug - no torque wrench)

 

Tighten down [new crush washer], loosen slightly, re-tighten. It won't back off.

 

This is how much to reduce torque from dry applications spec with different lubes added.
https://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

 

I like my arm for oil plug torque, hasn't failed me in 48 yrs! Tight + a quarter turn FTW! Good post BTW, need to account for lube.