Oil leak. Possible cause?

Are you sure there isn't any crack around the lower aluminum where you have the 12mm bolts?

If that checks OK, ensure that the stud in which the oil filter is tied to, isn't worn

PS: Another option is if the oil filter rubber seal on the filter is weak, due to the oil filter bring on the shelve for long.

 

Looks more like this bolt that's leaking?

 

That's the 12mm/14mm bolts in talking about.
But those shouldn't leak. If it's leaking around that region, there must be a crack, or the bolt isn't properly torqued

 

If its a crack, JB Weld works. Used it many times, even on a crack in an exhaust manifold.

 

But the problem is, if its a crack on that section if the lower oil pan, I don't think the JB weld is gonna work. I'm just concerned about the high oil pressures distribution in there. But if you've tried it, then that's cool. But that would be a short term fix. Isn't it?

 

Just for giggles, put a socket on it and make sure it's tight. Maybe it was removed in past and someone snugged it but neglected to torque?

 

odd spot

 

That's y you need a torque wrench, and a repair manual.

 

The other thing you could do that would permanently solve this is to aluminum weld it, when that part is removed. Tedious job though. Or you can have that part replaced

 

Am I the only one who gets annoyed when people don't use a torque wrench, and wonder if they under/over tightened something?

Per Toyota service manual:

• Oil Filter is 13ft-lb. A genuine OEM Toyota oil filter will say 3/4turn when oil filter gasket comes into contact with the oil filter seat of the engine block.
• The oil leak, dirt-greased, bolt in question is 18ft-lb.

Although the picture suggests an oil leak at the bolt area, I would replace the Bosch oil filter with a new OEM Toyota oil filter. Why?
For $4USD, the OP (Original Poster) might be able to rule out the bolt in question by using a new OEM Toyota oil filter. OP would have to clean up the dirty grease again as well. I have experienced a few cases where a new oil filter had a unknown bad o-ring, or the o-ring became bad, or maybe unseen debris came into contact with the o-ring.

Logic would say a bad oil filter o-ring would cause oil to leak to go DOWN the oil filter. Because of aerodynamics, and where the oil filter sits, at the end of the splash shield, it might be possible that some wind might be making its way UP into the engine compartment. This wind might drive some leaking oil from the oil filter to go UP and toward the suspect bolt near the oil filter.

If OP does this, and the oil leaking bolt goes away, the oil filter was the source of the leak.

If the oil leaking bolt reappears, then the bolt area is the likely source. OP is out $4USD for a new OEM Toyota oil filter and a few ounces of oil to replenish what was lost from the oil filter change.

Just dawned on me. OP could clean the dirt grease area now. Lower the car back to level ground. Force the engine into maintenance mode, so the engine is running; maybe let it run for an hour to ensure plenty of oil has been circulated. Jack-up the car and see where there is oil. If the oil filter, then the oil filter o-ring is bad. If the suspect bolt, then that area is bad, and maybe there is a hairline crack somewhere.