Eastman E8D issue with staying in tune…

Hey guys,

I own an Eastman E8D that I have been having trouble with. I play a lot of songs that are down tuned (Neil Young, specifically) so I have kept my Eastman tuned down a full step. I like how boomy it sounds with a dreadnaught.

The problem is, it seems to never stay in tune. And I mean that I will tune it, then 15 seconds into playing a song, it sounds out of tune. Sure enough, I check the pitch, and it is out of tune.

At first, I thought I was having intonation issues. But, the pitch seems to register exactly the same when open and when played at the 12th fret. I have been terribly frustrated by this as I love the guitar itself--it sounds amazing when it is in tune. But this issue has been driving me nuts.

Recently, I decided to tune it back up to standard tuning. Since doing so, I feel like the pitch of all the strings is so much better and so much more consistent. I don't feel like it goes out of tune like it did previously and I feel like when I pick it up, I do not have to tune up like I did when it was tuned a full step down.

Am I crazy? Is this a thing any of you have ever experienced?? Does keeping a guitar in alternate (lower) tuning make it more difficult to keep it in tune?

Any ideas what could be causing this? Do I need to upgrade my tuners? (I would think higher tension from standard tuning would cause tuners to go out of tune more frequently...not the opposite.) Could it be the strings?

Thanks for any input you might have!