Used oil in oil-burning lawn mower

[nbpt100]

Lots of good suggestions. I would not bother with using used oil. Most have said what I would have. A heavier than SAE 30 is where you want to go. If you are in warm weather (always over 50) try a SAE40 or SAE 50 if you can find it. It won't make a huge difference but it is worth a try.

I once has a mower that smoked a lot at start up. So I put in 20w-50 and that smoked more at start up than with the original SAE30. I Did not notice much smoking while it ran with either oil. I went back to the SAE 30. I think the lighter cold viscosity allowed more oil leakage into the cyl after it cooled down. You could also try one of the oil seal conditioner additives and that may slow down the seeping oil.

I think a 90wt gear oil is similar in viscosity to SAE 50 motor oil. But someone here will correct me If I am off on this.

 

[pcoxe]

Maybe it's not ring wear, but rather stuck rings. I'd try a piston soak with penetrating oil then a fresh oil change with synthetic. I've seen a few smokey engines tighten up after this treatment.

 

[Wrenchturner44]

There are labels all over the mower that say “cast iron sleeve”

Then it has the commercial grade engine. You might also be able to look it up by the serial number to confirm. I had a Snapper mower from the era with the Briggs 3.5HP engine. It was silica bore block. I verified this first hand when I tried to put new rings in it from heavy use on a steep hill. The engine had suffered from some oil starvation issues due to this compromise. Fortunately, I switched to a Lawnboy afterwards.

 

[gfh77665]

You need to immeadiatly drain and refill with HPL.

J/K! Amost ANY oil, used or not, is OK for a old mower like a 1980's Murray on its last legs.

 

[Lawnman23]

Then it has the commercial grade engine. You might also be able to look it up by the serial number to confirm. I had a Snapper mower from the era with the Briggs 3.5HP engine. It was silica bore block. I verified this first hand when I tried to put new rings in it from heavy use on a steep hill. The engine had suffered from some oil starvation issues due to this compromise. Fortunately, I switched to a Lawnboy afterwards.

You seemed to have missed the first post that stated it’s a I/C Briggs, Industrial/Commercial. As I mentioned earlier, all the I/C’s are sleeved.

 

[Wrenchturner44]

You seemed to have missed the first post that stated it’s a I/C Briggs, Industrial/Commercial. As I mentioned earlier, all the I/C’s are sleeved.

Yes, I missed that. That being said, I am also not aware that Murray or MTD used any commercial grade engines in any of their "consumer grade" models. Also most of the I/Cs of that era also came with larger fuel tanks I believe.....that was one way to also tell visually what the engine was.

 

[Lawnman23]

Yes, I missed that. That being said, I am also not aware that Murray or MTD used any commercial grade engines in any of their "consumer grade" models. Also most of the I/Cs of that era also came with larger fuel tanks I believe.....that was one way to also tell visually what the engine was.

Oh, they used them plenty. The I/C engines themselves were always marked as such:

The standard/non-I/C engines looked the part as well:

 

[Wrenchturner44]

Did they use them that much on the push mowers?

 

[Lawnman23]

Did they use them that much on the push mowers?

During the flat-head timeframe, not that I have seen/recall. Most walk-behinds would of had a 3.5 or 5hp consumer/base engine. Commercial walk-behinds very well may have had something better, back when quality was still regarded.

 

[fantastic]

Did they use them that much on the push mowers?

Think B&S called the small push mower engines "Aluma-Bore"? Don't remember for sure but they were mostly aluminum cylinder I think.

 

[kschachn]

Think B&S called the small push mower engines "Aluma-Bore"? Don't remember for sure but they were mostly aluminum cylinder I think.

Holy cow just plain aluminum? Nothing like Alusil or a coating like Nikasil?

 

[Dinoburner]

The world won`t end using used oil in a clapped out B/S engine However, here we use no-name cheapo 20/50 in a situation like that. Have a 12 HP in the barn waiting for it`s next duty station. Might re-ring if the mood strikes.