How to Find App Pool Recycles in Event Log

As it seems impossible to filter the XPath message data (it isn't in the XML to filter), you can also use powershell to search:

Get-WinEvent -LogName System | Where-Object {$_.Message -like "*recycle*"}

From this, I can see that the event Id for recycling seems to be 5074, so you can filter on this as well. I hope this helps someone as this information seemed to take a lot longer than expected to work out.

This along with @BlackHawkDesign comment should help you find what you need.

I had the same issue. Maybe interesting to mention is that you have to configure in which cases the app pool recycle event is logged. By default it's in a couple of cases, not all of them. You can do that in IIS > app pools > select the app pool > advanced settings > expand generate recycle event log entry – BlackHawkDesign Jan 14 '15 at 10:00

It seemed quite hard to find this information, but eventually, I came across this question
You have to look at the 'System' event log, and filter by the WAS source.
Here is more info about the WAS (Windows Process Activation Service)