Hokie is right.
The oil
was probably still doing a fine job. The problem with extended oil use is the package of supplemental "extender" additives that are added to the motor oil. Those don't last as long as the oil does and some of the additives can only do so much. Take acid killers. Once the acid killer changes the PH as much as it can, the engine can suffer acid etching.
Another additive suspends the combustion particles and surrounds them to prevent them from doing damage to the motor by getting them caught in the filter. That only lasts so long and then it gets overwhelmed. After that, small particles start wearing the innards.
My machine lucked out. It saw a ton of use, some of it running the rototiller for extended periods (that seated the rings for sure!) but the oil only sat in the engine for nine months. Yeah, it was a black mess of carbon but, the slippery part was still doing its job. I bet the additive package was just about shot. Though it sat outside its whole life, the engine oil showed no signs of water as it was run enough to dry out the crankcase each run.
Over time, mineral oil has actually been shown to wear down at the molecular level, mostly due to mechanical "shear" under load. Motorcycles are THE worst for this due to the gearboxes, and engine designs, comprised mostly of helical gears (cam drives in sport bikes) along with high horsepower loads. Synthetic makes sure that all the oil molecules are the same and that the oil is comprised of more of them, so losing a few due to wear means you still end up with mineral oil levels of protection by the time the oil is replaced. Oil viscosity changes over use.
One of the big reasons you want to get the oil out at 50 hours as well as swap out the hydraulic filters is to remove any captured metal left over from manufacturing. I saw zero metal when I did the first oil drain and any metal captured by the filter stayed there. Same with the HYD filters.
The head sales guy at my dealership recognized me in for parts one day and asked if I had found a machine. He remembered me looking for a used L3800. I told him what I had found and he asked me what I paid. I told him and he smiled and shook his head saying, "You got one
heck of a deal." When I told him the thing hadn't seen a lick of service for the first 126 hours he shook his head and said, "Not an issue. That is not long enough to do
any damage in nine months time."
Had my tractor sat for two more years with the same oil and little use, the result might not have been so positive. Today, I can start my tractor up after a week of napping and produces a small puff of grey smoke after a little pre-heat. I burn zero oil in 50 hours. I think the motor survived 126 hours of inattention quite well.
Lucky little machine. And, a lucky owner (ME!).
Ray
PS: For the bikers out there, here is an awesome article on oils:
http://www.nightrider.com/biketech/oiltest1.htm
Since reading this a decade ago, I switched all my bikes to Mobil 1 and have had zero problems.
