[AT] tractor oils maintenance?

[Greg Hass]

None of my tractors gets 100 hours a year even though I still farm some. 
I have never went with the once a year oil change but go by amount of 
use. However, none of my tractors see winter use except my skid steer 
which moves snow. That I do change in the spring due to cold weather 
contamination. Most of my tractors have an hour meter which I go by. My 
farmall cub has no meter so I guess at it. In fact it has been 6 years 
since an oil change and the oil looks like new but probably has only 60 
hours on it. Also, all my tractors are stored inside which makes a big 
difference in keeping moisture out. Another thing that helps is that, 
except for the loader, once my tractors are started they always have at 
least an hour run and usually 3 to 4 hours use to a start. I use the 
same system with  my lawn equipment and have never had a problem. Some 
may not agree with my system but each to his own. The one change I am 
making is I am cutting out the number of oils I am using and changing 
more of them to 15-40W oil. I will keep my IH 574 and 856 on straight 
30W because several people have advised me to stay with that on those 
old engines. My Cub has always used 20W but it is no longer made so will 
have to decide what to change that to.
        Greg Hass