If you are looking to fill up or replace the hydraulic fluid in the hydraulic lines on your Lamar trailer, you should replace it with AW-32. This is the fluid that the factory uses for your hydraulic pump lines. This fluid works for lines on KTI's hydraulic pump, hydraulic jacks, and hydraulic dovetails.
It's recommended to use premium oil, "Chevron Rando HDZ, Mobil DTE 10, DTE 20 series, AMSOIL, and Shell Tellus. Automotive Transmission Fluid (DEXRON III) are acceptable under normal conditions. Aviation Oils such as Valvoline ROYCO series or Mobil Aero HF or HFA may be used in prolonged, ex- treme cold environments."
Now, if you are in a bind and you can't find AW-32, you can also use non-foaming automatic transmission fluid, ATS. However, you will need to flush all of the other fluid out of the lines and replace it with this fluid. Do not mix AW-32 and ATS.
Sources KTI HYDRAULICS