Hello all, this is regarding our old International tractor with an D155 diesel engine. It runs good but consumes some oil and one thing we can blame for it is the rear crankshaft seal. Currently it is on its fourth oil fill of Mobil Delvac MX Extra 10w-40, a Gr. I/III based CI-4/SL lubricant. All in all, we have been using this oil for 600 - 700 hrs. With the drain plug on the side of the oil pan, it's easy to view inside when the oil is being changed. My impression is that the oil pan looks cleaner everytime. This cleaning proces has not really done anything to the crankshaft seal, I would say the oil loss is the same as before. Is there a chemical solution for this seal or is it simply worn? There are different opinions on seal conditioning out there, so what do you think a seal conditioner additive can do for this engine? If Valvoline MaxLife meets API CF, it should be able to protect this engine. Would MaxLife be an option? Since we use Delvac 1 in the other tractors, I have always been thrilled to use it in that old engine too. Has anyone ever "repaired" a high mileage engine with a synthetic HDEO?