BBT Vaginally?

I'm new to temping so any advice is welcome. I temped this morning orally same time & got a reading of 96.8 after that I got up and used the bathroom, got back into bed. 
As I was laying here, I was reading on Fertility Friend and it was saying how my temps were a little inconsistent and I could temp vaginally.. so I did and my temp was 97.5
I got a + opk yesterday.. just trying to see which would be more accurate for time in cycle.