I would run it as you have been until a major meltdown makes it impractical to repair. You already have about double it's normal life expectancy. Used tractors are always available.
Why is the Yard Machine being dumped after so little use? Somebody is mighty unhappy with it.

You're doing pretty good with this mower. You should be changing the oil, not just topping it off, and really should clean/replace the air filter more than once a year.

Nobody can say how much longer it will last, but quite possibly another 8 - 10 years.

As for the other mower you mentioned, I would not buy that machine.

Well, I've got 20 year old LT4000 with a briggs vanguard, engine runs like new with 160 lbs. of compression in each cylinder. Sure I had to do routine maintenance on it, but mine has atleast 3 times the hours if not 4 time the hours as your's.

If you keep it long enough even with good maintenance things will wear out. I had to replace the steering components, blades, spark plugs twice, bottom crank seal, seat cover, fuel pump, and spindle. Even got a new deck, not from being rusted through, but the underside air flow baffles welds had let go and I had to pull the baffles out. Still got the old deck which is not rusted or rotted anywhere.

So, If you would change the oil more than just Topping it off which is good keeping the oil level up, but changing it twice a year will make it last much longer and it may out live you? I suspect the engine will go bang one day if you not changing the oil?

Thanks for the responses. Yeah, I know I should have been completely replacing the oil these years, but I think I've only drained and completely changed it twice in those years. I forgot to mention I've replaced blades three times -- the last time was just a year ago when I put Gator Blades on it. BTW, The Gator Blades do seem to do a slightly better job of both cutting and mulching, but not hugely. They did do quite a nice job on my foot thick mounds of maple leaves this past Fall. The sellers of the Yard Machine say it's been in storage for three years. They say they used it 6 times before they had to move to a place with a much smaller yard and haven't used it since.

The craftsman lawn tractors offered in the 1990s actually held up well. Parts are still available and the tractors are easy to repair. The decks are also easy to remove and reinstall. Most probably (at 13.5 hp) you have the flathead Briggs. These were pretty good engines for most owners. I would expect you will find additional maintenance will be needed. Things like dry pulley bearings, cracked fuel lines, dirty cooling fins, dirty carburetors, dirty fuel tank interiors, and more - will need attention.

I would prefer your 12 year old mower over a 5 year old MTD.

This one has certainly held up well...I'm just wondering for how long. BTW, when I cleaned the fuel filter the other day, the carb just looked immaculate.

Considering that you never change the oil, i'd say you have been extremely lucky in not having the engine go "Bang"! So, in keeping with your el-cheapo maintenance schedule, you might as well keep on running it, until the engine goes "BANG" then go buy a new machine, and start over! But, don't expect these newer machines to give the same length of service, with the utmost least amount of care! They are built under the "Planned obsolescense" frame of mind. That is: If you get 8 years out of it--bend down onto yer knees and pray a prayer of thanks to the tractor Gods, for being so lucky! And, go buy another new one! Although, i firmly believe, by that time, the pollution gurus will have us all back to using walk-behind, unpowered, push reel type of mowers! (JMHO)Rustyj

I've got a 93 Craftsman 38" with the 14h.p. Briggs. 17 seasons still runs fine, deck is a little rough. I do change my oil every year regardless of hours. Its far from a full time mower now but it served me well. Typically the motors last longer than the machine. REJ2

Is it just me? IMO changing the oil once a year is not enough. It need to be changed in the fall after the summer heat, in the spring after fall use and setting all winter, and in the heat of the summer, which IMO is the most important so you have clean fresh oil during the heat of the summer when dust gets in the oil and most likely is when the engine will let got a connecting rod.

IMO you don't have to change the filter but once a year but pulling the oil out of the sump delutes the dirt suspended in the oil so the filter don't have to work so hard. IMO a quart or two of oil is cheap insurance for the long haul if you plan on keeping your LT tractor for 10 years or more.

Just finished my first mowing with Old Greeny. The grass looked like carpet after the uplifting cut of the Gator Blades that I had just sharpened to a scalpel edge.

Although, as I rode around grinning, I thought, 'Yes, old buddy, I should have changed your oil more, but there are enough camels in the world with solid gold watering troughs'.

I promise to change Old Greeny's oil. All the way. I promise.

If you sharpened those blades to a "scalpel edge", all you are doing is shortening their useful life. There should be a 1/32" flat left along the cutting edge to maintain blade strength and reduce metal chipping.
The sharpened blades also need to be precisely re-balanced after sharpening. Out of balance blades will put excessive vibratory side loads on your spindle bearings causing them to prematurely fail.

Oh, I am very careful with rebalancing after sharpening. I guess I must be doing OK since my spindle bearings have lasted 12 years.

FYI, this old 38" Craftsman is now 15 years old and may finally be on its last legs. This past Fall, it started just making a stripping feel when I would try to turn to the right -- and the steering wheel would turn but the front wheels wouldn't. I've looked down the steering column and there is significant wear of some toothed gear -- but just on the side where it would engage on a right turn. Engine runs great and mower cuts well -- but only on left turns. Looked up parts and it looks like they would be around $150 or more -- and I don't feel like putting that much more money (and repair time) in a 15-year old 38" mower.

Guess I'll finally be mower shopping this Spring and Old Greenie will be going up on CraigsList for parts. May just take her out back and put a .45 slug into the hood out of mercy, though.

I would think that you could come up with a method of mowing your yard, making only left turns. You might get another 5 years if that was possible.

You have never posted the Craftsman technical model number.
Post that number so we can see the steering system parts.
The technical model number is the 9 digit # under the seat on a decal stuck to the frame.

Craftsman Model # 917-270430

Yes, I see that your tractor has the HI$ steering system configuration.
I've not had to work on one like that yet, but I see where the parts list and cost could escalate pretty quick.
Maybe Tomplum will offer some advice as I bet he has had his hands on one of these.

I have a 1998 green era craftsman simular to yours,the plastic piece that your steering shaft slips into is worn out.You can drill it to fit a standard bushing from the hardware store.If the sector gear is not to bad it could be a $2.00 fix.

With all things considered, the op may do well with a shiny new penny. As far as steering repair on these, I always recommend installing a new sector kit. 167903 is the pre-built sector. Off the deck comes, the drag link end, the steering wheel and adapter, the fuel tank gets moved aside- plus4 bolts and the sector finds its way out. The part is ~ 80$. The drag link itself should be inspected and replaced if the joints are sloppy and may pull apart, Of course, that adds ~ 50$ to the bill.You will want to know too that the upper steering bushing has its mounting screws in place yet . The crosslink that runs between the two axle spindles can bend and create a poor steering response too, so have a look at that to ensure it is straight. While you can pull the sector and replace the plastic support for $10. I never do as it seems that the rest also has enough wear once problems develop- that skipping can still occur or it will come back soon enough to bite you.

I have read this thread, and while the OP is proud that his mower has lasted so long, I get the feeling from reading his post that he is trying to make a case to get a new mower.

If so my recommendation is go for the new mower. It does not matter how good the tractor is and how well you have taken care of it the desire for the new mower will continue to get stronger.

It is nearing the end of January, John Deere and some of the other manufacturers will be having their Spring Specials so you can get a good deal on a new tractor.

As the desire for a new tractor increase, the deals will become better.

PS Sorry I hope your wife does not read this forum

Thanks for all the input folks, but my last post in which I talked about the steering problem was basically my declaration that -- yes -- I am getting a new mower.

I do not feel inclined to put any significant money (even if it's much less than a new mower) into a 15-year old mower. Plus, it looks like fixing this steering would be a fairly significant task involving multiple hours, serious cursing and head-scratching. So, I think I'm going to put Old Greenie on Craigslist for a couple of hundred bucks and take any best offer I get there.

I am going to be checking out Spring sales big-time and think I am very interested in a rear-engine rider. The reports of great front visibility and tight turning circles really sound good to an old Craftsman owner.

Any of you have any experience with the Snapper or Troy-Bilt rear-engine riders and want to share your insights on those?

So the wife does read this forum, ;-)

Sorry I messed with your subtle tactics to get a new mower

Free tractor: I was given one of the old green model of C-man lawn tractor, free. So, i took the parts off another one of similar age, and it now steers like it should. When i told the PO about fixing it, he got upset! Dunno why. It runs well, deck needs some TLC. It'll get sold in the Spring.
I also bought another one of same time period. Has a good engine and tires, and parts. Might put that engine in a different machine that has been loafing around for several years. Too durn cold right now to do anything but set by the stove. RJ