15w40 for 125k good or bad?

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Jim b

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Based on my experience it is highly unlikely that running a 15W oil would hurt any engine.
Yes cold oil flow is important however a 15W will cushion the bearings during a cold start. The main reason for the low viscosity oils it to improve fuel consumption when cold.
For the next 200k miles I would be way more worried about the $40,000 that I would be spending on gasoline!
Cheers
Jim B
 

bigdog9191999

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I wouldn't worry too much about it really, there is a good chance they ran it because once running it was used and ran consistent ( either highway or idle) I have run some rotella in several of my vehicles (15-40 t5 or t6) as well as my motor cycles. as long as it was changed regularly it should go for a long time.
 
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slowride

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OK sounds like it probably wouldnt have hurt anything then. I do remember seeing something about one of the cats having been replaced like somebody mentioned before, not sure if that was related to the oil type or what though
 

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