Thanks guys, I'll give them a try. How do you guys do with starting your Power-Trac in cold weather? Mine has the 15W oil for the hydraulics and it start painfully hard. I'm wondering if the 10W-40 would make a difference since its lighter?
Mine starts to -5F, but I have a Kohler engine. I have been using Mobil 1 5w30 in the engine since the first oil change, and at each 50 hr hydraulic filter change I've added a quart of Mobil 1 5w30 or 40 to top it off. So, with about 500 hours, the stock 40 quarts of 10w40 that came with the unit has been diluted with 10 quarts of Mobil 1.
You might want to check the specs on the cold viscosity performance of 5W, 10W, and 15W oil. I think that you might be surprised. There isn't much difference. There are lots of threads elsewhere on the forum.
For the 425s, the tank heaters seem to be the consensus best solution if you don't have a heated garage.
With cold oil, there is always the risk of cavitation in the motors, so it is a good idea to keep the throttle down until the oil is warm.
Wow! It sounds like the Kohler has an advantage over the Robin Subaru. Have you ever heard what the reasoning was for replacing the Kohler with the Robin Subaru? Its an awesome machine and I love the design of it, but its more cold blooded than any machine I've ever owned.