A have a 1 ounce bottle of poplar bud oil that is about 5 or 6+ years old. Never used any of it. Looked at it today and it is so thick (like tar) that it won't pour from the bottle. Still has the nice odor...just very thick.

Will this thin back up with some gentle heat?

Good poplar bud oil is very viscous by nature. Warming will help thin it some, however it will still be syrupy in nature if it was good material to begin with.

Thanks Bob!