K161 oil change, help?

[LAWN BOY]

I found Traveller brand 30W in 1 quart bottles at Tractor Supply. I did some research and found that it’s made by Warren in the USA.

[Farmall450]

Originally Posted by RoseHillFarmIHCC125

I use Rotella 15W-40 in all my stuff. Never had a problem and I change it once a year. I used it when I overhauled my K301 last year, ran it for a few hours then changed it. Oil technology has came a long way since ‘68 when my 125 was made.

Yeah, honestly anything in the right ballpark would work.

[greg r]

These air cooled engines tend to have "looser" fits with cylinder bore to piston clearance running in the .007" - .010" or more depending on run time. For a diameter just under 3" that's almost twice what a car engine is. The 30wt oil the factory specifies provides a good layer against piston rocking/scuffing when first started cold. Things really work together as run time warms up the parts and decreases cold clearances while at the same time the oil thins from the heat.

It's only when the temps go below 32* that the oil charts show either a 10-30 or 10-40, that being initially a 10wt.

I saw that in the worst with a 1946 two cycle engine I bought years ago that was a year or two on it's overhaul. I asked the PO why didn't he use 50wt in the mix like the book sez. He said it's a 2 cycle and oils have come a long way so he used 2 cycle oil though the ratio was correct.. After I bought it I found it had little power and the cylinder needed a reboring over size. I talked with the head mechanic at the factory and he pointed out piston clearance was why they still specified 50wt in the mix. 30 years later after my overhaul, it still needs only 1/2 throttle to do the work it used to take a full throttle when I first got it.

I know 2 cycle and 4 cycle are apples and oranges but it does show what the right oil can do.

[RoseHillFarmIHCC125]

When I overhauled my K301, I had to go with a .030” over piston.