What do you guys use for checking oil level on the RTAC? The IOM says to use 2 charging hoses with a sightglass in the middle. The oil line valve on mine is a 3/8" fitting and the discharge service ports are 1/4". Trane sells a clear hose with both ends being 1/4" but they don't sell any fittings to hook up to the 3/8" side.