Sorry for responding to my thread so late, been a busy time around my place.Think you mean 5-40 on the T6. 15-40 is the conventional in the white jug.
They all foam a bit when running. Best time to check the fluid level is dead cold after sitting all day.
Neither of mine have a sight glass, only a dipstick which is often hard to read so what I did was drill a small hole at the full mark and one at the add mark so when I pull the stick out, if it's full, the oil will bridge the hole making it easy to see. If neither hole is covered, it's low and needs topped off. I go through a bit of hydraulic fluid as I'm always changing out implements that have hydraulics on them and every time I disconnect the hoses, the quick disconnects weep a bit of fluid. Keeps the back end well oiled.
Lots of cars are like that today, I'm surprised that Kubota never did that. Even my lawnmower is set up that way.
My engine oil was T6 fully synthetic 15w-40 Shell Rotella. They did have the T5 15w-40 sitting next to it however, which is what you are thinking of. It is cheaper, and not fully synthetic. This is what I got:
Questions like this regarding the hydro oil puzzle me. My co worker got a new M7060 kubota just after I got my new L2501, and he says his 50hour maintenance did not call for changing the hydro oil either - his doesn't even call for changing the hydraulic filter until 500 hours! He is one of the folks I have leaned on for advice. he has collected and rebuilt antique tractors his entire life. He has around 60 antique tractors and other farm equipment and had over 100 tractors in his hay day. Anyways, his 50 hour maintenance was nothing but engine oil and engine oil filter. Thats all it called for. Some slightly older Kubotas called for changing the hydro oil at 50 hours. There has to be a very deliberate reason why this change was made, but I have found in the world of tractors its hard to cut through peoples personal opinions and bias's that have baked in for years to find the actual truth on things like this. I haven't owned or worked on tractors enough to delineate the reason myself yet. But, it has to be something where they feel there is no need in doing this at 50 hours any longer in these machines, and I have no doubt they wouldn't put this in their owners manuals and recommendations without strong, clear evidence. That said however, as in most things, you certainly cant hurt anything by doing it anyways. Its one of those things that it can ONLY serve to do something positive for you. There is zero negative or risk, and only positive upsides if anything is to gain from it. I do still wish I had drained the last bit of oil out. My filter magnet had only very very tiny hair like material on it - and it was just a little pinch of it. I saw no big metal shavings or anything like ive seen on some folks videos.
I still havent got to do any work on the tractor since the maintenance. Hoping to do something this next weekend. I need to move some fencing for our horses. Im coming up now with an easy, fast way to pull Metal t-posts with the tractor, without bending them. Any ingenious ideas on this front? Ill come up with something Im sure.