Mobil 1 extended service oil

SouthArk370Z

I'm curious as to what those reasons are.

As has been mentioned before, for your circumstances, it's not usually dirt or oil degradation that is the problem, it's the acids and other crap that get in your oil. Need to flush that stuff out on a regular basis.

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Darwins Child

I just spelled them out.

What "acids and other crap" get into the new oil after draining the old oil, putting in the new oil and then not starting the vehicle for 6 or more months?

SouthArk370Z

You did a piss-poor job.

Unless you are cleaning/flushing the engine before putting in the new oil, it's the same crap that was there before you did the oil change. It will be less concentrated than before the change, but still there.

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Darwins Child

I believe that draining old oil that has been warmed up shortly before draining, and then allowed to drain for a good long time, removes all but a very few drops of that contaminated oil from the engine. Removing the old filter completes the process.

I have to start the engine to move the vehicle from its position in our garage where I change the oil to its position in the same garage where it will be stored for the winter - a move of about 5 feet parallel to the east. After adding the new oil, the engine will run for perhaps 2 minutes to make that move and this will be enough time for the new oil to be circulated within the engine, wetting all its oiled parts and rinsing off into the oil pan any old oil still clinging to those parts.

IMO, this new oil in the engine after this 2 minutes of running will be no different than the new oil in the engine after any oil change performed at any other time under any circumstance. That is, after draining old oil, most people don't normally flush the engine with new oil, drain that, then refill with new oil and filter. The oil change before storage be no different.

The few drops of old oil remaining in the new oil can sit there in the new oil, as it always does. The only difference this time will be that the engine will sit for several months before going into normal operation again. The internals of the engine, having had all old oil rinsed off, will not be exposed to the normal contamination process, or the miles, that usually ensue after most oil changes.

SouthArk370Z

Modern oils have additives to make them "stickier" - they leave a film on everything.

You are not rinsing, you are diluting. Nothing gets moved to the pan, it's all mixed together.

Exactly.

While doing a change will greatly reduce the amount of contaminants, it's more than just a few drops of "bad" oil remaining in the crankcase after draining.

Change your oil (at least) twice a year.

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