For a lighter-weight hydraulic fluid, you need Skydrol 5. With its lighter weight due to a lower density, you can save fuel and see an overall cost savings. At higher temperatures, you may experience erosion, but Skydrol 5 is the first aviation hydraulic fluid demonstrating erosion-resistance at higher temperatures so that you can experience decreased maintenance and downtime.ture conditions. With PE-5, you can experience less frequent fluid replacement, reducing disposal volume and decreasing your environmental footprint.