[AT] Question about modern 4WD tractor (while watching Oliver Super 77 Diesel)

[Grant Brians]

This question is probably directed primarily at Mike Sloane as he has recent
experience with New Holland 4WD tractors. I have been driving my 1996
NH6610S with mechanical 4WD ripping fields. For those not in California, we
typically mechanically work the vegetable fields 2-3 feet deep to break up
hardpan, aid in leaching salt from irrigation water and ease root
penetration every so often. To eke out the last horsepower out of the
tractor and aid in traction, I am running full time in four wheel drive.
This is nominally about an 80hp tractor, but it was dyno tested at 93hp just
before I bought it by the dealer. In the loam and clay soils (heavy...) that
I work, I'm running 3 shanks between 20 and 28 inches deep in third gear at
around 3.5mph.
    The question is, using the full power of the tractor as I am, am I
hurting it? I don't think so, but would like some feedback.
    Also, I must comment on the Oliver reference in the email title. One of
our Olivers is a Super 77 Diesel wide front with cultivating bars. It is the
preferred tractor by the renter's tractor drivers for seeding with their air
seeder and other things - they much prefer it to the modern (last ten years)
tractors they were using before! It is smoother, quieter and just easier to
operate - except for that lack of power steering and even that is not enough
to overcome their like for the tractor.
        Grant Brians
        Hollister, California