I looked at your 3535 manual and here are some of the things I came up with:
In general change the hydraulic and Hydrostatic filters and the fluid at 50 hours then at 350 hour intervals.
Also clean the hydraulic strainer at every hydraulic fluid change.
Use a high quality fluid, that is common to most of our tractors, see the list below. I use Mobil fluid 424 which is also on your list
Shell Spirax/Donax is also easy to find and on your list.
As pointed out it wouldn't take 5 minutes to uncouple your quick connects and put them back on.
Here is the manual URL:
Adding Hydraulic and Transmission Oil
Oil for hydraulic system & transmission is common in this
tractor and reservoir for this common oil is the transmission
case. Change Hydraulics and Transmission oil initially at
50 hrs. and subsequently at every 350 hrs. of operation.
While changing, oil has to be filled in rear housing.
Check the level of oil in the transmission & hydraulic
reservoir as follows:
Hydraulic and Transmission Suction Oil Filter
Change Hydraulics and Transmission oil filter (A) initially at
50 hrs. and subsequently at every 350 hrs. of operation.
These Spin-on type filters are located behind on RH side of
the tractor. Remove old spin-on filters.
Prime the new spin-on filter with clean oil, and fit them
Hydraulic and Transmission Strainer
Clean suction strainer during every oil change. The suction
strainer (B) is located on RH side of rear housing and can
be removed as follows:
1) Remove suction filter of Hydraulic & Transmission.
2) Remove the Cover Plate (B) by unscrewing four bolts.
3) Pull the suction strainer out from housing.
4) Clean the strainer in clean diesel fuel, using a soft
brush, then blow dry with compressed air.
5) Refit the strainer.
6) Refit the cover plate and suction filter.
For Service / Replacement of strainer contact your
Mahindra Dealer.
Hydrostatic Transmission (HST) Oil Filter
Change HST oil filter (A) initially at 50 hours and
subsequently at every 350 hours of operation.
Transmission, Hydraulics and Oil Immersed Brakes
Use mild EP type gear lubricant. They should meet API GL4
performance category with suitable additives compatible
for paper based brake liner and taking care of noise. Use
viscosity based on the expected air temperature range
during the period between oil changes.
Please refer Oil Specifications Chart for oil specifications at
different range of ambient temperatures.
Following oils are recommended.
1. GULF Universal Tractor Transmission Fluid
2. Exxon Torque fluid 56
3. Shell Donax TD
4. Mobil fluid 424
5. Tractelf BF 12
6. Tractelf C4 - 1000
7. Hydro Clear Power Train Fluid
Other brands may be used if they meet all the specifications
and performance levels of the above.