I've got my "4026" diesel project all buttoned up and ready to test drive and I had about 7 quarts of oil left over from the rear axle and engine (nicely enough they all use 15W-40). I poured the 7 quarts in and it doesn't even register in the tank. No oil on the ground either so it's all in the tractor... somewhere... Leads me to this thought: How much oil did these things need stock? I have poked around and most say 10 quarts but if that was the case I'd at least be able to see some oil in the tank by now I'd hope, I didn't add that much hydraulic capacity with return lines and such. Going to acquire at least 10 more quarts this weekend and give it another go. When I get it running and moving I'll post a video here assuming it doesn't obliterate itself or me. This is a 1978 model 444 originally with the plastic tank in the control stack behind the steering wheel.