rear main seal

[attack on track]

If the oil level is topped off and perfect, and the 99 GMC 454 crew dually has been sitting for 3 full days.....Will there be oil on the ground if the rear main seal has even a slow leak?

(parked on level concrete)

Thanks in advance.

 

[DerekTheGreat]

My vote is no. Well, if it's leaking it might leave some drips after being driven but once all the oil settles back into the pan it won't leave any more drips.

 

[attack on track]

Thanks Derek.
I have been driving it quite a bit the past 2 days. Each time I park it somewhere, I check for even one drop--nothing.

I would see something if it were in fact a rear seal, correct?
I feel there was a misdiagnosis. The "oil sending unit pigtail" was replaced after a large oil leak in January. That old oil leak would still be a mess in that area, and could have someone believe there is a rear main seal leak, correct?

I have never seen any sign of oil (other than on dipstick) since I bought it, and have been scratching my head since that diagnosis. I appreciate any insight or thoughts.

 

[Kenton Ahrens]

Oil can either come from the oil pressure sensor if not properly screwed in all the way or even under the distributor, if that gasket is gone. There is a gasket between the distributor and the intake manifold that is often overlooked.
Also the rear main seal may start to weep oil after 100,000 miles. Not enough to drop constantly but always some after running. Unfortunately, the first two are easier to fix. That last would require to drop the tranny to fix.

 

[DerekTheGreat]

Yes, if the RMS was leaking you'd see a residue left behind on your oil pan at the back between the inspection cover of the trans and maybe some leaking out of the bell housing. Mine is leaking again despite having a shop replace it. That or my input shaft is leaking (Manual trans truck)