I was using outdoor decking oil on my teak hatches, dorade boxes and strakes. I found they were quite okay. The only difference was that they do have some ferric oxide in them for UV protection, which does leave a slightly orange tinge. This 'tinge' also marks
paint and
gelcoat unless it is removed immediately after being spilled, splashed or otherwise comes into contact with non timber surfaces. I think in terms of durability, exterior decking oil is better than
marine teak oil. It is much less expensive, but the orange thing may deter you.
I guess outdoor teak oil may also contain ferric oxide, but a quick look at the ingredients will tell you that. The only other thing I would be concerned about is if the non
marine product contains any
varnish. If it does, there is the problem of whether it needs to be removed or abraded prior to recoating.
I found that oils lasted about three months before needing a recoat. But, that
boat was kept in Darwin, northern
Australia, where the sub equatorial sun is relentless all year round.