Mixing oil types

[bob888]

A friend sold his plane and had a case of Aeroshell W100 left over, which he gave to me. I am using Phillips XC 20/50. Is there any compatibility issue with the oil types? I would like to use the W100 as 'add in' oil.

 

[Mel]

No problem. The oils are compatible.

 

[lr172]

One should never mix different weights of multi-weight oil. Mixing straight weights is ok. Something about viscosity modifiers doesn't do well when mixed. I suspect adding straight to multi is not an issue.

Larry