There was no abnormal pump noise at all. Everything sounded normal. I do hear a normal pitch (to an HST whine) change when the tractor warms up like I would expect. The DPO had a Fram engine filter on the tractor so he may be the type that might have bought the Supertech 303 hydraulic oil (not rated for HST from what I can tell) I saw at Walmart after seeing the post above from 100 td about the better SuperTech hydraulic oil. Sorry to those that might use Fram.
He did have Kubota filters on the hydraulic fluid, but that might have been since Walmart doesn't stock those sizes in Fram.
The tractor does not creep at all with the foot off of the fwd/rev pedals. I only set brake because it was a slope, mostly in case the tractor shut off for some reason.
On the oil testing, can they tell you what type of oil? ie gear, flushing, UDT, etc?
That's good about the not creeping; to my mind it means neither the brakes nor HST is the problem.
On the lab, I don't know. If you do check with your lab please do post what you find....I don't know if mine can or not. Maybe I'll give the local one a call.
Can't resist the fun of a bull session and speculating - so my bet would be that some labs can and others not and it doesn't really matter because none of them I've heard of actually do that. The labs I've dealt with expect you to tell them about the basic oil you are putting in along with as much more info as you can.
What I look for - and hope not to find - from the oil lab's report is any unusual change in the proportion of certain mostly metal ions in the oil. Numbers that are out of line with the amount you would expect from that many operating hours on that oil. An example would be babbit or bushing bearing material in the oil. Bushing materials have a a specific analytic fingerprint. Any lab can and will spot it. Just to increase your tension, there will always have some. So the question becomes, "Is it significant?"
Is there more wear than last time or less?
Then there are things like beryllium, lithium, or moly friction reducers that are part of the additive packages in new oils and that get plated out on the inside of the engine so that their numbers decrease. And you'll see a pH change if any water got in there - but pH is linked to the gross amount of metal and carbonate ions so it isn't all that easy to sort out what it means.....things like that. Labs I've dealt with will usually help with the interpretation on things like pH. I always get that interpretation wrong myself. And it's up to you to decide if your operating hours are working the machine hard in tough rock, road time, or just idling. The hourmeter doesn't know nor care.
I love lab work and think it is worth the cost. But honestly I don't think I've ever once found out something I didn't already know or suspect. Sure is fun though...
On oils and filters I tend to use OEM filters and the factory recommended oils in my own machines. But that is more for mental convenience than any real knowledge on my part. After half a century of wrench bending plus an engineering stint - my own belief is that there is only a slight different in how any modern oils affect wear in an engine/tranny in moderate service. But foaming is NOT normal.
My recommendation is to leave your filters alone and just swap the oil out for something standard and dinosaur that you know won't hurt the HST. Something like NH MultiG 134 or JD 303. Use standard viscosity rather than low viscosity.
Luck,
rScotty