Originally Posted By: A_Harman
Don't do it. AMSoil states in all their product data sheets not to mix anything into their oils because the long-drain interval ability will be lost.
Almost every company says the same thing in regards to mixing oils and additives.
Originally Posted By: Amsoil
Mixing AMSOIL motor oils with other oils, however, will shorten the oil’s life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed.
Originally Posted By: Mobil 1
the superior performance of Mobil 1 will be reduced by diluting it.
Originally Posted By: Pennzoil
It is advisable that you use the same oil for top-ups if needed, thereby giving you the best protection from the oil that you have chosen.