Thanks for the reply Tinkerer.
This is the original 1997 engine in a Poulan garden tractor, to which I added the ground-engaging-implement assembly. It gets in excess of 100 hours a year now, so that alone would be about 2500 hours. The first 10 years or so it was likely getting about double that as it was being used much more for things in addition to ordinary mowing like rough-cut mowing, hauling gravel, tilling, rock raking, and sweeping cut grass for composting and mulch. I even did a little garden soil plowing with it, but didn't have the right tires to do much of that-and it was only capable of doing shallow work. due to belt slippage and not enough weight. So my best guess (without an hour meter, one of which I have on the shelf but never got around to installing) is that it has something like 3500 hours on it.
I've worn through one mowing deck until, despite painting, coating, recoating, sandblasting and painting, coating, recoating and patching, it was like tinfoil in places, and replaced just about everything else on this machine at least once-some things multiple times, such as spindle assemblies, pulleys, steering gear assemblies, steering axle assembles, starters, carburetors, magnetos, wheel bearings, (plus tires belts blades, spark plugs, and filters of course), but it still has the original hydro and engine. Although I am using a heavier weight gear oil in the engine and hydro than it started with.
The last time I had the heads off they were carboned up of course, but they cleaned up same as always. (A long time ago I polished the heads inside to make cleaning easier and slow carbon buildup and also installed solid steel threaded spark plug inserts when one stripped.) There's been no significant difference in the valve or valve seats recently-with no evidence of overheating or cracks on the valves themselves. I've lapped the valves in their seats just a bit with valve grinding compound a couple times over the years to be sure they have decent seating surfaces,
The ridge was more pronounced on one cylinder than the other, with more wear on the bottom/ground facing cylinder sides as would be expected.
I've tried using different weights of single grade oil after having used Briggs 30wyt throughout the warranty period. As soon as the warranty ended I switched to Castrol 15w40 and ran that and an extra length filter until about 3-5 years ago, when oil consumption started to gradually increase. 40wt is consumed at about 1 to 1-12 ounces an hour, 15w40 at about 1-1/2-2 ounces ounces per hour, and 30wt about 2+ ounces per hour. That's if I use a GOOD oil, like Castrol or Rotella (which i use in our diesel tractors). I tried a tractor supply house's own brand of 30wt and that ran through at about 3 ounces per hour. I can deal with the 40wt and one ounce per hour consumption for about 2/3 of the year here but its getting to be a hassle and I think that this engine has earned its retirement. The tractor itself probably has too, but it has a lot of low hour parts on it now so........ .......
I should have included where we live in the first post-its East Tennessee, 37727.
