There are a lot of advantages and disadvantages of both water based and oil based decking oil. Depending on your needs, one can be more suitable than the other.
Water based-
Positives:
- Fewer odours
- Quicker to dry
- Longer lasting
- Easy Cleanup
- Holds colour better
Negatives:
- requires sanding to remove the oil (costly and time consuming especially if used dome headed nails)
- Opaque look which somewhat hides the natural grain of the timber
- Usually more expensive
Oil based-
Positives:
- Requires little effort to remove oil
- Easy to apply
- Penetrating
- Great durability in harsh conditions
- Greater UV protection
- Enhances the natural beauty of the timber and its grain
- Less time consuming in the initial coating, recoating and removal
- Water repellent
- Usually Cheaper
Negatives:
- Ideally need re-coating every 12 months
- Strong odour
- Requires more frequent maintenance