HT25 - LUBRICATION 67 With frame level and digging boom fully raised, check oil at sight glass (2) every 10 hours. Add THF at fill (3) as necessary. Clean dust from cap by blowing with low-pressure air. Drain hydraulic oil (1), change filter (4), and refill with THF every 1000 hours. Change oil and filter every 500 hours if jobsite temperature exceeds 100°F (38°C) more than 50% of the time. Change oil filter at 50 hours and every 250 hours thereafter. p Hydraulic Oil HYDRAULICS Check Change