1999 BMW 328i Smoke coming from engine bay?

It is coming from where the o2 sensors are & sometimes behind the motor. Replaced the Valve Cover gasket, used high temp rtv as well. I also changed the spark plugs & put 5w30 castrol edge (titanium) in it. I did not replace the grommets that go on the bolts though. Idk if that may be a possibility? Or if the oil viscosity is too thin. It was not smoking before. I had to rebuild the VANOS unit. That's why I did everything else.