Losing fresh oil faster than old oil

[mattt]

04 Tahoe with 250k on the engine. I have the 5.3 Z"flex fuel" engine. It has the typical oil leaks that most all 5.3's have. I have noticed, right after an oil change that my oil level drops quicker than once the oil is a bit older. To explain better....in the first 3000 miles of oil usage, I typically have to add a quart of oil. In the last 40% on the oil monitor, or last ~3000 miles of an oil change cycle, I barely have to add half a quart. Is it typical of the 5.3 to burn thru or leak fresh, clean oil at a much faster rate than used oil that has been in a for a while?

I've seen this happen repeatedly, so I think I am on to something, meaning this isn't just a one time flash in the pan. I've observed this over the last 12-18 months and 3 oil changes.

 

[retiredsparky]

Could it be that new oil is thinner? As the engine accumulates miles, the oil could get thicker and lose less past the rings.

 

[mattt]

That's exactly what I was wondering.....if fresh oil has a smaller molecule that will slip past leaky seals and gaskets easier than dirty oil.

To swerve this thread....where are the most common leak points on a 5.3? I would like to seal this back up, and I seem to remember hearing there are common leak points.

Oil pan, rear cover, valve covers?

Is there a write up here for replacing the above seals/gaskets?

 

[79jasper]

Iirc, oil actually looses viscosity. (Could be wrong though)
You sure it's just leaking it, and not eating it?

Sent from my SM-G892A using Tapatalk

 

[mattt]

I think it could be doing both eating and leaking....as we all do


I just know after paying closer attention to it, I have to add more early on vs. later on, in the oil change % cycle. Thanks for the info about viscosity.