I have a 2009 Highlander, automatic, 6 cylinder, AWD with 180,000 miles. There is a slow leak around the oil pan gasket. Tightened once then replaced and torqued but it is still leaking. The instructions said don’t use sealer. How do I stop it?
The same car has a very slow leak from the timing chain cover. The dealership quoted $2800 to fix it due to having to lift the engine to get to the cover. Poor design.
I may have to sell it and go back to the 4Runner.
The reason Toyota probably doesn't recommend using sealer is they're concerned it will get squeezed inside the oil pan and clog up the oiling system.
The lip around the oil pan can become bent from prying the pan off. The bolt holes in the oil pan can also become bent upward from over tightening the bolts.
If this is the case and you don't want to buy a new oil pan, then sealer will probably need to be used sparingly. If nothing is bent and an aftermarket gasket is being used, maybe it's just a poor quality gasket and an OEM Toyota gasket would work better and not require any sealer.
If the pan still leaks and sealer is required. I've seen spray can sealer used to hold the gasket in place on oil pans to help with installation. If squeeze tube sealer is used make sure to apply a very thin bead so the sealer doesn't squeeze out inside of the oil pan and clog up the pickup tube, variable valve timing solenoids, and oil gallery passages.
Video of what happens when too much sealer is used.
https://youtube.com/shorts/QTtb5MuOeJw
Video of proper oil pan install using gasket sealer.
Video showing the proper bead size for gasket sealer and how to tell if too much is squeezing out.
The downsides of sealer is it makes a mess and doesn't last as long as a gasket. I've heard that's why Subaru's have so many leaks, due to sealer being used instead of gaskets during assembly.
Here's the fixed video link on sealer bead size and how to tell if too much sealer is squeezing out. https://youtu.be/xMWsQWcMcWY