I changed my oil from a standard grade to a synthetic grade (Royal Purple) and now see that I have a leak. My guess is that making the change is what cause this.
If I go back to standard grade any thoughts as to what if any leaks would continue? Yes all things were tight and done right.

 

The first question is where is the new leak?

 

looks like its coming right were the engine is connected to the trans ?

 

That's a very good question. Had 92 Jimmy 4.3L bought it with 100k miles, ran it for another 100K miles using synthetic blend oil, no issues. 2004 avalanche 5.3L 130K switched to full synthetic 2 years ago, started leaking and burning more oil. Considering switching back to the blend before pulling the oil pan. Try to find that happy medium somewhere. Found some information on this subject, thought it was interesting, hope it helps.

 

Thank you very much. Very Helpful.

 

If you have oil dripping from the bell housing area, the possibility it's coming from the main seal. The best way to tell is to pull the flywheel cover off the bottom of the bell housing and look up at the rear seal and look for wettness. might use some brake or carb cleaner to get it dry. Don't rule out the fact oil can also run down from the back of the intake manifold and valve covers.

 

RBB: Welcome to the forum. Hope you find that it's a valve cover gasket as the rear main seal is not easy to replace.

 

looks like its the Rear Main seal.

 

That's not good news, you have several options, I think. Try an oil synthetic blend (high mileage)or try a main seal additive (many on amazon) they cause the seal to swell, or replace the seal. You can try other things before you replace the main seal. I'm not sure how hard you drive but older engines with higher mileage have more blow by. Back in the early 80's when working at a chevy dealership I replaced many main seals in GM's early diesel ideas, the converted oldsmobile 350 to a diesel (very bad idea). One of the main issues was the main seal leaking oil, we replaced many. GM decied the problem with that was the older the engine got the more blow by it had and it pressurized the crankcase and pushed oil out the main seal. The fix was better ventilation on the valve covers, less internal pressure. (they used rope main seals) RBB take a good look at your engine vent system first to see if it has an issue or could be improved, for a start.

 

A rear main seal replacement is not a difficult job on your car. Once you have your car on ramps or jackstands you can disconnect the tie rods and swing them out of the way. The oil pan can now be removed without obstruction.