Good afternoon! I have recently purchased a 1999 C5 and was told that it was not leaking. Surprise, it is leaking. I did the dutiful research and went to You-Tube University and felt that I would at least change the lower pan gasket, I mean how hard can it be. I am not a mechanic but have virtually been able to repair all my vehicles in my garage with no issue. I put the car on the lift to complete the work and discovered that my batwing looks very different than what I can see on the web. There are no forward bolts, by the drain plug and the pan appears to be a single pan, molded on what normally would be a the upper pan. Has anyone seen this? It is the manual six speed. The block appears to be very dry and the balances just appears to be normal grime under it, nothing above it with no recent wet under it. The pan is filthy wet (batwing) I am looking for direction on this one. I don't have the ability myself (no engine hoist) to do all the work behind changing what I would think just be the normal upper pan gasket. Surprisingly, the upper pan gasket is more readily available than the lower one. I would assume that if this is indeed a single body, it would just require an upper pan gasket. I think I am losing my marbles. I spent a full hour underneath the pan, trying to figure out why mine is different. Like an idiot, I did not take a picture of it. Help anyone?

 

Welcome, moving you here to C5 Tech

 

Found it, Google did not have it, but Ebay did. Apparently the L6 has the same pan. Description is 1 piece batwing oil pan.

 

welcome

 

As you have discovered, there were, indeed, two different "bat wing" oil pans used on the C5. The early model was one piece, while the newer model was two piece. Beyond affirming that nugget of information for you, I'm not sure how I can help.

Since I know absolutely nothing about your car, except that it is twenty-five years old and it has an oil leak, I feel ill-informed to participate in your poll.

 

Yes I believe the factory switched to the 2-pcs batwing oil pan #12561828 as part of the updates and improvement done to the '02 LS6 engine, at least that what it says on page #267 of the 2015 GMPP catalog;

https://www.superformance.com.au/***...0Catalogue.pdf

 

Let us know if the pan gasket solves your leaks. I have a 99 and it's filthy wet all over the pan, but I'm putting my money on the crank seal because of the wobbly balancer. With a 25 year old GM engine, they all leak somewhere..... Especially mine with 172k miles,

 

My 2000 C5 came with the 2pc pan......

 

Exactly, not sure if there ever was a consensuses as to when the switch to the 2-pcs batwing pan was actually made. I had thought is was with the '01 model year and the introduction of the LS6. When was your '00 built, possibly late in the model year run?

 

Yes. Though I don't know what would be considered late model year, my 2000 was built in March or April of 2000. So imho, it is a late model....

 

I think if you could support the engine somehow then you could lower the suspension cradle and replace the pan gasket. This should be easier than trying to pull the engine out from above. Is it a 4-post or 2-post lift? I just pulled my rear suspension, differential and transmission on my 4-post and it wasn't that hard to do.

I have a 98 and it has a 1-piece pan on it. I also have an early LS1 with perimeter bolt valve covers and it had a 1-piece pan, that I put a cam in and replaced the pan with a truck pan for a C10 swap. I'd bet money this engine was never opened before I took the pan off it. I believe perimeter bolt valve covers are a 97-98 or 97-99 thing so this engine was pre 2000 as well as the one in my car. I'd definitely expect to find a 1-piece in a 99.

 

The '97-98 LS1 in the C5 came with the 806 head casting and the perimeter bolt valve covers. In '99 LS1 in the C5 switched to the 853 heads along with the center bolt valve covers. My '99 LS1 came with the 1-pcs bat wing oil pan, but I swapped it out for the later 2-pcs unit so that I could utilize the Improved Racing trap-door oil control baffling inserts.