Let me start by saying these funnels are a lifesaver for messy oil changes. The flexibility is their biggest selling point - you can twist and bend them to fit into tight spaces where traditional funnels would fail. I used the green one to drain oil from my motorcycle, and it conformed perfectly to the awkward angle near the drain plug.

The material feels more like thin silicone than rubber though, which explains some durability concerns. While testing, I noticed they hold basic shapes well (like a simple U-shape for draining), but complex folds tend to collapse under fluid weight. Not ideal for filling operations as some reviews mentioned.

Temperature resistance is impressive! I left one in my freezing garage all winter and it remained pliable. During summer oil changes, hot oil didn't deform them either. The color-coding (red/green/blue) is genius when working with multiple fluids.

Major drawback? They're ridiculously easy to lose! Like another reviewer, I've nearly thrown mine away twice already because they blend with shop rags. At this price point though, losing one doesn't hurt much.

Final verdict: Great as disposable/replaceable drain guides, mediocre as actual filling funnels. Keep expectations realistic and you'll find them useful for what they are.