You don’t have to pull the engine to replace to replace a rear main seal or the front timing cover seal. But you do have to pull the pan to replace the rear main seal. For an occasional drop from it I wouldn’t bother as rear seal replacements always have a risk of an uncertain outcome depending on engine parts condition and care in replacement assembly.

 

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Is the "front timing cover seal" the same thing as "front main seal"? In my picture(s) above I just presumed there was a "front main seal" because I've heard the words "rear main seal". Also in my pictures above, I simply called them RMS and FMS drop zones without really knowing what the source of the drip is.
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On a somewhat related note, I have been using Mobil Delvac 1300 Super 15W-40 engine oil which is a synthetic oil and will be changing my oil very soon to Driven HR5 engine oil which is a conventional engine oil, so hopefully the switch to the conventional will help a little bit with the drips (doubtful but hopeful). I can also try some of that Blue Devil rear main sealer that was suggested early in this thread. I want to see if the switch to a conventional motor oil has any effect before adding the blue devil product.
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Here's some pix of my cardboard from just a few seconds ago... I drove the car about 36 hours ago and I haven't driven it since so any/all the drips you see on the cardboard have occurred after that first drive 36 hours ago. In the past 24 hours it appears that the front drop zone hasn't changed much while the rear drop zone has collected a few more drips.
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both drop zones, drips collected over ~36 hours

front drop zone, drips collected over ~36 hours

rear drop zone, drips collected over ~36 hours

the oil I previously used and is the oil currently in my car's engine

the oil I'm going to use with my next oil change (which could be any day now)

 

I have a new oil fill cap in place that should prevent oil from leaking out. Now I'm going to take the car out for another drive to see if I have any fluid leaks anywhere and will share the results (good or bad) soon. Fingers are crossed.

 

I have been through two caps on my chevelle and all of them leak a little bit of oil

 

Yes, the timing cover seal is the front seal. Your cardboard is showing enough to tick me off over time and plan a winter project. But I might try a bottle of Blue Devil first. They make one targeted specifically at rear seals which are typically similar in composition to the front seal.

https://www.autozone.com/p/bluedevil...hoCrlEQAvD_BwE

 

In case you're not aware, there are actually three sealing components on the front of the engine. There is a pressed-in seal on the timing cover that the crankshaft protrudes through. That seal actually seals on the hub of the harmonic balancer when it is installed on the snout of the crankshaft. There is a gasket that seals the flange of the timing cover to the face of the engine block and there is a seal at the bottom of the timing cover that seals the timing cover to the oil pan. All of these are potential leak points, so it's best to determine exactly where your oil leak is coming from before you start any disassembly.

Ted

 

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Yes that's the same bottle I have sitting on my toolbox just waiting to use it if necessary.

 

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Thanks for laying that out for me. I was not aware. It's hard to imagine what all these seals and gaskets look like. Maybe one of these days I'll get the courage to find out.

 

YES!!! FINALLY!!!
With a new oil fill cap in place my son and I took the car out on Saturday 5/9/26 afternoon (2PM) for the same drive I did a couple days before. And the results (so far) are EXACTLY what I was hoping for. Let me show the pix and then I'll explain what the pix mean in relation to the goals of this project...
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New/repro oil fill cap with a stout rubber gasket contained oil with no leaks

This is what I've been waiting to see
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You might recall from an earlier post (from a couple days ago) that I had just gotten back from my initial test drive after replacing the intake manifold gaskets and seals along with the valve cover gaskets when I placed my fingers under the passenger side valve cover flange and found lots of oil on my fingers. Seeing the oil I thought that I had failed in some way and then I realized that the oil fill cap had been allowing some oil past it.
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I now realize that the oil I saw on my fingers a couple days ago was coming from a prior oil fill cap AND NOT FROM UNDER THE VALVE COVER!!! This means that perhaps all the hard work I've done may have paid off. I feel like this is the first time I have good reason to hope and expect the desired outcome - to prevent oil leaks/drops from the intake manifold and valve covers.
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Below is a picture taken on Sunday 5/10 morning of the new cardboard placed under my car after the drive on Saturday 5/9. The same familiar drip coming from the rear main seal area but interestingly there isn't a drip (yet) under the front main seal area.

Same drip from the rear main seal area but interestingly the drop zone from the front main seal area is dry (today)
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I know things can change at any moment but at this moment I am very pleased with how the intake manifold seals and gaskets as well as the valve cover gaskets seem to be holding for the first time since I've owned the car!!!!

 

And here is a picture from right now. The rear main seal drop zone looks a little bigger than yesterday at this same time...

5/11/26 @ 11:15 AM CST

 

Excellent outcome, Brian, congratulations!

 

Perfecto! A job well done!

 

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Thanks guys. I was just the guy turning the wrench, taking the pictures, and telling the story. The unnamed guy who was coaching me through all this from 500 miles away has been a fantastic teacher and a good friend, and is the one who deserves all the accolades.