My Farmall 706 which I use for lighter jobs like pulling a planter and cultivating began fouling plugs. The engine had new sleeves, pistons and rings not over 250 hours ago five years or so back. It never has used oil. Now a couple of the cylinders are going down. The plugs were full around the insulators. The tractor would sort of put out a light white smoke when the plugs were fouled. In my opinion it also used the 15w-40 weight oil.Here is what I have done different this spring right before this started: 1) I drained the straight weight 30 and put in 15w-40. I did this to reduce the kinds of oil I had to keep around. Oil salesman said it would work. If figured it would be a heavy duty oil and good for the engine. I guess there were alot of detergents in this oil. 2) Years past I had been running gas bought at a convience store. Some of it may have been gasohol. This spring I had the bulk truck come and he left tractor fuel. It would have some additives to act like lead. What do you guys think is up? I replaced the plugs and the tractor runs fine with good power. After some time a plug or two will load up. I have drained the 15w-40 oil and replaced it with SAE 30. The plugs are either Champion Y-15D or D-15Y - can't remember. Even after I changed oil it fouled a plug. Do you think the oil cleaned the engine out too much? Also does the 15w-40 slip past the rings easier than the straight 30? Could some of those deposits on the plugs be from the gas additives? Do I need hotter plugs to burn the modern tractor gas? I guess I got to remember that it really consumed the 15w-40 oil. It drank one-half of the crankcase in 14 hours. I told the oil salesman and he immediately offerred a free 5 gal pail of SAE 30. The oil was Archer. Ideas???? I just want my old 706 back!
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