Hi, folks - I took my '96 Subaru Outback Legacy with 136,000 miles on it in for a routine oil change tonight to a quick change location - and was told that the cap was seized and could not be removed without breaking it off. Any recommendations about what to do next?
thanks
peacechild in Central Ohio
Then, break it off, and then replace it. Autozone and Pep boys have inexpensive caps for all kinds of cars. The dealership should have plenty of factory replacements.
BTW, how long has it been since any oil was added to the car? I’ve had stubborn caps before, but never one that seized up completely. I have had some break, which is how I know how easy a replacement can be found.
I’ve sometimes had this trouble when the engine was hot. The oil cap came off easily the next morning from a cold engine.
So, had they already drained your oil when they discovered the problem? What did THEY do next?
You may have to break it off. Channel lock pliers work well. BTDT
It was perhaps 3 months since the oil had been changed - I’ll try it when the engine is cooler. I wondered if the temperature had anything to do with it - it was in the high eighties here today. They didn’t drain the oil because they couldn’t get the cap off. They basically said - sorry about your luck, take it to a mechanic. I’ll check with AutoZone on the part - I’ve not always had good luck with after-market Subaru parts.
It’s reassuring to hear others have been there.
Thanks, everyone
I’ve sometimes had trouble removing the oil filler caps on hot engines, especially valve cover-mounted caps. I’ve been able to fit a set of slip-joint pliers onto stubborn caps and remove them that way, if the need was dire. I bet if you try when the engine is cold, it’ll come off easier because you can grip it without burning your hand. 
Just another reason to stay away from the Quickie-Lube butchers. Can’t even remove an oil cap, and suggests taking it to a real mechanic. At least they acknowledge their limitations this time.
There may be another place it could be added using a funnel, PCV or breather tube opening.
At least they tried to get the cap off before they drained the oil,someone was thinking
Lay a bag of ice on top of the cap for about 15 min then try to loosen it.
Use of a strap wrench should work without damaging the cap. When reinstalling the oil filler cap, there is no need to tighten to gorilla torque.
The cap on my old pickup used to stick too. I took a short piece of strap metal, drilled two holes the appropriate distance to mate with the “teeth” on the cap’s circumference, putting in two bolts secured with nuts, and used it for many years.