It is possible to change the finish of a 15 mm engineered flooring - sanding the floors to remove existing finish is required and new finish is applied. If the product you have is 3-strip, I would believe this product has 3 mm top layer 'though, which does not change the situation, but such products can take restoration only once.
In your question about the finish... Oil based products may be easier to maintain - in case of scratch or wearing you can rub some oil with cotton cloth on the floor and it will blend the damage.
Oils & Hardwax-oil are not hard-wearing sealant though. A better, requiring less maintenance finish is the varnish.
In short best advise for durability of finish is:
- Good hard-wearing product, such as "Bona Mega" or "Junckers Strong" or their 2-part, commercial grade alternatives "Junckers HP Commercial" or "Bona Traffic HD". These in combination with Matt or UltraMatt sheens will give you good protection and make any future scuffs and scratches are less visible.
- "Bona Naturale" - combines best of all finishes, highest durability, can be repaired (like oil), natural matt sheen. Downside is cost - double the cost of some other finishes.