I decided, now that Spring seems to have decided to come, to change the oil in my little diesel tractor. It was easy enough to get the plug out, drain the oil and refill it. But I don’t have an oil filter wrench - how bad would it be to run clean oil through a dirty filter? The oil was about two years old, but only about 50 hrs of work. It was pretty black, though.
StG
You can remove an oil filter without the special wrench, for example punch a screwdriver into the filter:
If you’re going to do your own maintenance on the tractor, then you need to invest in some basic tools. An oil filter wrench is one such tool, and it is cheap.
Seems like every time I buy something with an oil filter I need to buy a new oil filter wrench. Buy a new filter and take it to an auto parts store and try the different oil filter wrenches until you find one that fits.
I did this once when an oil filter was really stuck on my old Duster. When I tried to turn the filter with the screwdriver, the thin sheet metal of the filter ripped, and I ended up with the jagged stump of an oil filter still stuck on my engine.
That said, on that car I replaced the oil at 4000 mile intervals and the filter at 8000 mile intervals, and it only lasted 175000 miles. 
I’m sorry, but I have to recommend against this. In the best case, it will work and spill oil everywhere. In the worst case, the filter housing will shear off and leave sharp metal edges to cut up your hand and wrists, all with the stuck-on filter stub remaining.
For the OP, I recommend the Lisle universal wrenches, https://www.amazon.com/Lisle-63600-Oil-Filter-Tool/dp/B0002SR4Q8 (regular sizes), or https://www.amazon.com/Lisle-63250-Range-Filter-Wrench/dp/B0002SR4PY (large diameter filters).
My current yard tractor cost 7 grand. the right oil filter wrench cost about $5.95. Easy decision.
Yeah, I guess a filter wrench is in my future. Thanks for the advice.
StG
One more vote that punching a hole through the filter could rip the whole thing apart and leave you with a useless filter stub stuck on the engine.
But, I think changing the oil without changing the filter is much better than not changing either. I read that the oil chemistry changes and it gets thinner and less friendly to metal, which you’d be fixing.
I’ve used a sheet of sandpaper wrapped around the filter for grip, and removed it by hand. This has worked most of the time.
I’ve improvised a “strap wrench” (is that what they’re called?) using a piece of rope and a screwdriver.
There should be no problem using the old filter for another cycle.
Oil in diesel engines gets filled with particles of combustion byproduct faster than in gasoline engines because, well, diesel. I mean look at all the black exhaust you get when under load.
I haven’t owned an oil filter wrench in over 40 years and have had zero issues getting old filters off. My oil filter wrench is my 16 inch Channelock pliers I received as a Christmas gift from my mother. I think of her every time I use them.
The oil in diesel engines turns black pretty much right when you start it after an oil change because, as GaryM says, it gets filled with particulate matter from combustion.
I’ve had good luck with oil filter pliers without having to buy different dedicated wrenches… You do have to be cautious using them to tighten as too tight a grip in the middle of the filter can crush the filter.
Well, as it turns out, I have some time to get the wrench (or borrow one) because I checked the manual and online repair site and neither gave the size of the oil filter. I ordered them from an online site and will have to wait for them. Got some new fuel filters while I was at it.
StG
Other folks will have their own opinions. I suggest that you look at your Factory Service Manual, (FSM). It will have the recommended times & hours (of use) between oil changes as well as fuel & air filter changes. The manufacturer will always recommend changing the oil filter when you change the oil. This is the answer to the original question.
The key to getting the longevity out of a diesel engine is to keep it clean! In other words, change the oil, the oil filter, the fuel filters, & the air filter fairly ofen. If the air filter is an oil bath style of filter, it should be serviced fairly often. Once a month may not be often enough. In dusty conditions, like most lawns, every other mowing might be about right, assuming your lawn is about one acre.
Since you asked for advice, I will give you mine. Changing the oil every two years is not often enough, even when used infrequently. The oil builds up contaminants that are very hard on diesel engines. The oil will be on the acidic side. Do you really want to have a small vat of a weak acid below your engine for over a year? I do not.
Of course it is your tractor, your time, & your money, do as you please. I have no skin in this game, but I like to help when I can.
BTW, I am a diesel mechanic that became an aircraft mechanic partly because I was tired of being filthy every day. Keep it clean.
IHTH, 48.
PS. The oil bath air filter is the best kind, but most garden tractors have a paper element style. Since most homeowners will not service an oil bath style often enough & the manufacturers do not like warranty work, they install the paper filter.
Missed the edit window. The five minute rule must be from the time you start to type, not from when you post it.
Do not tighten the new filter with a wrench, hand tight is almost always just fine. Look for leaks after installation. If necessary use the wrench. In over 40 years, I have never found it necessary to use a wrench to get the filter to seal.
Looking at my FSM it stays to be careful to not over tighten the filter. Doing so can cause the seal to fail, it can cause the element inside of the filter to fail, & it can also cause the filter to be very difficult to remove.
Again, do as you please.
IHTH, 48.