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OK, I did a real bone head move. I was changing my oil and dumped in 2 gal of Rotella 15w40 that I just bought at the store and grabbed the half empty bottle from the last oil change and dumped it in without checking the label only to see afterwards while cleaning up that I used 2 qts of Rotella SAE 30 that I use in my lawnmower. Should I be worried?
 

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I wouldn't worry, especially in cold weather. Maybe change it out a little sooner next time.
 

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Mixing oils

Was the oil ( S ) spark or the (C) compression oil? That you added if C then not so bad. I am going with the C oils now for every thing, pay alittle more and good to go.
 

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OK, I did a real bone head move. I was changing my oil and dumped in 2 gal of Rotella 15w40 that I just bought at the store and grabbed the half empty bottle from the last oil change and dumped it in without checking the label only to see afterwards while cleaning up that I used 2 qts of Rotella SAE 30 that I use in my lawnmower. Should I be worried?
WarpathEngineering,

So you'll know that this information is correct, I am a retired lubrication engineer from Allison Transmission and General Motors. I do a lot of advising on the forum and you can find me under "Former Allison Transmission Fluids Engineer".

These two oils are completed mixable at any ratio. So, you really haven't done a whole lot of damage that you need to worry about. The effect will be that your cold start cranking torque may go up very slightly (probably not noticable unless you're in an extremely cold climate) and the viscosity at operating temperature (around 100C) will be slightly lower. An oil analysis would show this to be true..

Hope this helps !!!

Here's a link to a paper I wrote that might help you: http://www.jglubricantservices.com/docs/Technical%20Information%20Sheet.pdf

PS: This information is not intended to as a "sales tool". Oil analysis is available through several sources. I'm just trying to help you out.
 

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No problems, won't damage/hurt anything but:
If it's going to keep you up at night , change the oil (and get some sleep):)
 

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Tom's got you covered on this - great article!
 
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