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Extra Mineral Oil

J

JDA_BTR

Well Known Member
I'm 30 hours into my engine break-in. Changed the oil at 5 hours. Going to change it now. In 25 hours it will be time to change to ashless dispersant oil (which one - oh no!). But I will have many quarts of the 100 mineral oil on hand when the break-in is done....

So - do I just stay with mineral oil to 80 hours?
Or - do I go ahead and switch at 50-55 to the new oil and then what?

I suppose there would be no harm in using one of the mineral oil quarts occasionally when a quart low?
 
I vote give it to someone that can use it. Once the break in is complete you dont want that in your engine, it doesnt clean the engine and suspend particles the way AD oil does.
 
Yep that?s a good idea too. I read my io390 manual and it says that I should check the screens and chainge the oil again 5 hours after the first ashless dispersant oil change. The context might apply to older engines it isn?t super clear. I never read anyone doing that here.
 
There's absolutely no problem mixing straight mineral oil in with AD oil.
I would use up the mineral oil one quart at a time with your AD oil.
 
JDA_BTR said:
Yep that?s a good idea too. I read my io390 manual and it says that I should check the screens and chainge the oil again 5 hours after the first ashless dispersant oil change. The context might apply to older engines it isn?t super clear. I never read anyone doing that here.
Click to expand...

Remember too that the longer you wait to change to AD the more crud you might have from the mineral oil not having the dispersant properties. Changing around 50 is a good plan and that was verified by Jeff at Lycoming. FWIW, at around 50 I changed to AD in my 390 and the screen was clean of any crud.
 
Has oil usage stabilized? Most manuals I have seen tell you to use breaking oil a certain number of hours or until usage has stabilized.
 
Thanks Mel. It makes sense it would be fine as a practical matter. Not as a purist though. The old joke about mathematicians and physicists comes to mind.
 
You can?t be serious, it says aviation oil on the bottle. It lubes the engine. It likes other oil too. :eek:
 
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