Rear end oil question

Sun Mar 10, 2013 6:31 pm

Not a Cub question but I changed the rear end oil in my IH 240 today for the first time in 15 years or so tractor has never spent a night outdoors and I did not see any water, but what I did see was foam. What would cause a lot of foam in uncontaminated oil. Is it possible for the anti foam agents just to wear out???