Hello all! So I just bought a new to me truck, 2010 Silverado LTZ with the 5.3. I had one before this one so I was familiar with the truck and loved it, so I got a newer one that was nicer with less miles. I've had this one about a month and it's started leaking oil. I didn't buy and "warranty" or coverage on the vehicle from getting screwed on my last vehicle, so it is going to be me or my mechanic fixing it if it needs something significant. I noticed the oil leak about a week before writing this, so I went up to AutoZone, bought all new Castrol GTX oil, new K&N oil filter (only type I run), and some Lucas Oil engine oil stop leak (I heard it was good stuff). I cleaned the underside of the truck really good the day before, I changed the oil, and I look under the truck a few days later and it's still leaking the same amount and same places it was before. It's blowing on the sway bar when I drive so it's hard to tell where it's coming from. I've seen drops hanging off the transmission service cap, dripping off the oil drain plug, splashed on the bell housing (not really dripping from there, just looks like residue), and the place where the oil pan area and the bell housing meet (not the bell housing itself, but that area). Some of the areas that look dry and have been known to be problem spots are the oil filter, oil pan gasket (the front 3/4 of the pan are bone dry on mine, just the back part towards the rear of the truck), and the cooler block plate (don't really know what this is, but it's behind the starter and I read on some forums to check it and it appears dry, BUT I'M NOT RULING THIS OUT BECAUSE IDK WHAT IT IS). It's dripping very slightly, only a few little drips a day, but I want it fixed. I've read where it could be the rear main, the oil pan gasket, the rear cover gasket (not sure what this is either), and maybe as simple as a bad washer on the oil drain plug (getting one of those soon). The truck has 118k miles on it and I'm just wondering if I'm missing something. I'm by no means a mechanic, but I read forums a lot for advice and I'm definitely YouTube certified Any help would be appreciated, I just hope it's something I can do myself. If not, that is ok too. I don't have pictures of the truck as I am on my desktop, so I tried to be as descriptive as possible. Thanks and God bless!

 

post some pics.
stop leak products are junk..they swell rubber hoses, gaskets and orings...do not use them.

 

The pictures aren’t very good but I won’t have a chance for a while to post some more. This was right before I changed the oil after I cleaned it good

 

oil leaks will flow from top to bottom and front to back.
pan out with the pics
in the one pic of the trans...there are 2rounds metal plugs...remove them and look up onto the flex plate...if its clean there...the rear main seal is ok.

 

Will anything leak out when I open those? And do I look up toward the top front of it like I’m trying to find the rear main or just look in general? Thanks!

 

Nothing should leak out - they are for inspection and accessing the torque converter drain plug. If there’s a leak, you will see oil has been “thrown” around the inside of the trans housing. A light film is nothing to be immediately worried about, but if it’s been collecting and dripping out the bottom, better to fix it sooner rather than later.

A leak inside the trans housing doesn’t automatically mean the rear main seal is the source - there’s 2 or 3 oil galley plugs as well.

There’s a UV dye that can be added to your oil to help isolate the source.