RETROGRADE AND COMBUST SEVENTH LORD

[Passionforastrology]

DOB: 30.5.1982
TOB: 02.10 AM
POB: Bangalore.

My seventh lord mercury is retrograde and placed conjunct with sun at 4 degrees between them in third house. Sun also happens to be my sixth lord. I have read several articles which say that retrograde mercury is combust with 12 degrees of the sun. I have also read many other articles which say that a retrograde mercury and direct venus can never be combust, no matter how close they are to the sun; in fact their significations are not destroyed and on the contrary they become much more powerful and yield even more better results.....which of the two concepts is true? BTW in my navamsa, i have direct venus conjunct with sun in the eigth house...i dont know the degrees between them though.