The transmission/hydraulics is easy and will use Universal Transmission/hyd Fluid (UTF)

I have not seen any comments on blended synthetic or full synthetic such as the Rotella 10-30 T5 or T6.  Is there value in the extra $20-30 cost/yr for T5 or T6 vs. "regular" T4? 

I also know many add Zn additives, but not sure if that is a good idea with synthetic blends or full synthetic.

I don't want to add something that loosens up all the sludge and damages the engine and maybe stick with a good 10-30.  Will take the valve cover off this weekend and see if there is much build up (the engine has been rebuilt to some extent at somepoint in time since the front pully is the newer style without the crank slots).

Thank you!

  You last statement saying that you don't want something that will loosen sludge will be nearly impossible to find, since nearly ALL Non-Detergent oils are NLA.

  If you are just using your CA for normal use, I'd suggest something like Shell Rotella in a T4 version, anything newer will not have the Zinc needed for your camshaft. That's just my opinion, you're bound to get many different ones.  I don't know about other brand oils. Shell RotellaT and AMZOIL are the only Oils I use.

Todays motor oils far surpass anything made when these Tractors were new. I run standard Cam 2, or Vavoline 10w30 motor oil in my big Tractors and never had any problems. I do run Royal Purple in my ZT mower and mainly because of the size of my lawn and the summer heat. I'm out there for about 3.5 hours mowin' and I'm rockin' and a rollin' with that Badboy mower. That 27 horse Kohler is hummin'. That machine just turned 14 years old. I also run synthentic in the other small mowers. Again, mainly for the heat they can create in the hot summer. My one Toro push mower, that was pushing 10 years old, the deck rotted out and the engine still ran fine. Still have the engine for a spare yet on the shelf in the garage. Buying another mower was cheaper than buying just a deck at the time. That bugger still ran great with the synthentic in it. I also just run standard 5w30 in my Antique cars as well. Soooo... I guess its just up to the individual what they want to run in their machines...

Steve@B&B

Was mowing the back yard and the RPM started to drop, thought it was tough grass but continued to drop and then a tight squeaking sound to shut down.  It was hot, and no oil on the dipstick with vapors coming out.  Didn't have any 30wt at the house but did have some ATF for some reason.  The motor was locked so I put ATF in the crankcase, let it cool and then worked the blade back and forth to get it free enough to spin.  Got it cranked and it squeaked for a bit, kept running at low rpm and slowly gained rpm.  After a couple minutes it ran full rpm and I finished mowing the yard.  Figured it was probably junk but ended up putting 30wt back in it and continued to use.  I still have it and it still runs although I haven't needed it in a few years as I can get around everything with the rider.

I try to use synthetic in all my newer engines, but did not want mess up this engine.  Appreciate the perspective of avoiding newer oils with the tappet cams and etc.

Love the lawn mower story. Amazing how they can survive.  Reminds me that I have always wanted to set up a betting pool for how long a car would run without any oil. I have heard that they can run for hours!!!   Maybe someday!

Thanks again!!