did i harm my car by putting 15/40 oil in it? and would it be okay to now add 10/30 oil to that?
Mar 30, 2009 at 8:01 AM
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DOCHAGERTY
CAR REPAIR CONTRIBUTOR
9,606 POSTS
In a word, no, you did no harm. I would run it on 15w40 if it were mine and adding oil of different viscosity is frowned upon by the oil engineers, but I have done what you want to and have combined oils without causing harm to the engine.
Mar 30, 2009 at 11:22 AM
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