I've noticed some loose rust on the tip of my dip stick when I check the oil level. I was pretty sure it was coming from the dip stick tube and not the oil pan, but it was hard to diagnose with the intake manifold in the way.
I removed the intake manifold since I wanted to replace its gasket anyway. This gave me a real good look and I could see oil was leaking where the dip stick tube meets the engine block. I cleaned away all the crud and then pulled the tube. The o-ring was bad. The 10mm by 2mm o-ring cost $2.49 from Toyota or 24 cents at your local hardware store.
I have a small spiral brush with a 20 inch flexible handle just for situations like this. I snaked it through the tube with some penetrating oil and it cleaned up real nice. Slipped on the new o-ring and reinstalled it. Problem solved, not to mention intake manifold gasket replaced. I'd encourage everyone to check this when you replace the infamous intake manifold gasket.
Bill
