CHARLIE - Those fiberglass golf cart conversions were kinda cool. Can't say I've ever seen one in person. I don't think I ever saw a picture of one like the top one with the bodywork up along the engine. Or one with a mower deck mounted like the second one. Looks like there's PLENTY of room to carry a large cooler with plenty of your favorite refreshing beverage for mowing the back yard on warm sunny days.
BILL J. - Summer of '80 I borrowed Dad's #70 to mow my little yard one day in the late summer. Made up my mind I was gong to have my own CC by the following spring. I could have bought several semi dump trailers full of green/yellow tractors but finally found my #72, first CC I saw advertised in the local paper. Think it was the 2nd or 3rd week of Jan '81, so in round numbers I've had it 32 years. The #70 I borrowed from Dad he bought new spring of '65 according to it's serial number. I put a boat-load of hours on it when it was new. It's sitting in my shop slated for a refurbish starting later this morning. It will be a l-o-n-g process. Has to be done by spring so SON can mow with it. I've had my 982 since Labor Day weekend of 2000, so just over 12 yrs. Not sure I'll look for a replacement for the 70 but I might. I doubt I'd get another Super, but anything other than an Original or Q/L is possible.
Far as your question about using 15W-40 diesel oil in a Kohler, I've used Shell Rotella in all my CC's, Kohler & Onan both, since 1996 when I got my PSD. I'd also use Mobil Delvac, or Chevron Delo but I won't switch from one to another just because it's cheaper. I am using Rotella 5W-40 synthetic in the K321 in the 72, and will use it in the K241 I'll put in the 70.
The little bit of engine work I've done to my PSD since I've had it, mainly replacing the glow plugs under the valve covers, the tops of the cylinder heads were spotless after 250,000 miles when I changed them. Both the Super H & '51 M had used a multitude of cheap oils before I got them up here and switched them to Rotella. The M was actually sludged up pretty good, and after two oil/filter changes with Rotella it's really clean inside the engine now too. Rotella's soot control detergents really clean up a dirty engine.
Another really good oil for air-cooled Kohler's and probably Onan's is IH Ashless motor oil in straight 30 weight. It will actually clean the hard carbon deposits off exhaust valve stems which is the reason Kohler engines stick the exh. valves, also can be caused by running too lean on the carb settings. And IH's #1 30 weight or 15W-40 diesel oil would be O-K too.
Dad had a couple old CC's that were smoking on start-up and burning oil. He switched to IH Ashless 30 weight and the smoking stopped and oil use dropped to about 1/4th of what it had been.
I understand there are some changes going on now with the old IH engine oils now that New Holland has taken over and been in control for several years. The old IH engines seem to have a healthy appetite for the new engine oils that they didn't have with the older IH oils so your results may not be the same as what My Dad had. And last I knew, the IH Ashless 30 was maybe going to become NLA.