Odd man out . .
I have this unit and find it usable and providing good, but not outstanding, views in the cylinder. It is the best unit for the dollar I have found though. Although a little short on resolution, the focal length, depth of field and articulation are spot on.
For the price you would likely find it returning more value than it's cost, I have.
I recently got a $50 borescope for a .22 rifle. It has much better resolution and while perfect for its application, I don't think it is usable for an engine due to focal length and rigid probe. It makes me hopeful a low cost unit with much better resolution is possible.
As the search for a better scope continues, this is best found.