Old oil in mower through winter?

[rob-the-oil-nut]

"Old oil OK for 20-min flush?"
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=14;t=000201 is a bit old and this is sort of a different matter.
Same oil (10, 15, or more years old but in sealed containers) and same mower. FWIW, mower engine seems to have eaten a fair amount of oil through the summer (more than its capacity) and the oil was very black (I have until spring to decide: Should I do Auto-RX, then LC, in a GC or Diesel-rated 15W40, or use crappy oil until it dies?)
This old oil that is OK for a 20 minute flush: What about draining the oil now, in fall, and refilling with this old oil. Then in spring either run 20 mins and drain after the engine runs (certainly under 1/2 hour) on the old oil, and replace with (new) straight 30 (as the manual & dipstick say) or something like the aforementioned HDEO / 15W40 / GC / Redline, etc.....I just somehow sense there is something wrong with this plan.
If the old oil would be OK for a 20-30 min "flush" why wouldn't it be fine to sit in the sump for 5 months? Again, to be clear, I do not want that old oil *running* more than 30 mins before discarding it.
Thanks!
Rob-the-oil-nut

 

[Brett Miller]

You can change to oil in a mower for less than $2. It's false economy not too change it before winter storage.

 

[Bror Jace]

rob, sounds like whichever plan you follow, you'll be giving that machine better care than 95% of the owners out there.

I'd use the old (but clean) oil for storage with no reservations.

--- Bror Jace

 

[rob-the-oil-nut]

You are absolutely correct, Brett. But it's more than the $2 or even if it's twice that, it's the pain of doing it, in an unheated garage, considering we aren't sure we won't be mowing one more time, and it is unlikely to get above 50 F (or 40?) any time in the next week, and from there on it may be 8+ months before it hits 40 again. Then there's disposal of the old oil...
I'm beginning to see how this effort is more than what 95% of mower owners are willing to put up with

(Thanks for the reply Bror!)
So if I do change it and we decide to do another mow, how bad is that going to be on the mower?
Are additives that are over 15 years old likely to be precipitated / resistant to mix in the oil as they should, or of significant potential of harm? How many hours of operation is too many? (I doubt it will be beyond two hours of operation, worst-case scenario)
THANKS
Rob

 

[Bror Jace]

Rob, I'd pour the oil out of one quart bottle into a clean second container. See any strong trace of residue at the bottom of the original bottle?

I'd use 15 year-old still-in-the-bottle oil without concern ... just not for any kind of extended or heavy duty. For just a couple hours use? No problem.

As I've said to others, a lot of owners use 15 year old oil in their mower ... it's the same stuff the mower came with 15 years ago.

--- Bror Jace