20W-50 motorcycle oil in mower?

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May 7, 2018
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Northern KY
Somehow I ended up with a few quarts of 20W-50 NAPA motorcycle oil even though I don't own a motorcycle? Is there any reason I shouldn't use it in my Briggs & Stratton two cylinder mowers? My instincts tell me it would be fine.
 
What does your Briggs engine manual say on oil?
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It says this, but I’ve used 15w-40 in one of them for several years and it seems to do fine. When I replaced the crankcase gasket the internals all looked brand new.
 
The main difference between motorcycle and automotive oil is that motorcycle oil doesn't have friction modifiers due to the wet clutches used in many bikes. It probably has extra anti wear additives, too. Use it in your OPE with confidence.

My rider doesn't seem to mind the Havoline 20w-50 that's in it currently.
 
Somehow I ended up with a few quarts of 20W-50 NAPA motorcycle oil even though I don't own a motorcycle? Is there any reason I shouldn't use it in my Briggs & Stratton two cylinder mowers? My instincts tell me it would be fine.
(y)You will be more than fine and that oil will certainly take the heat of an air cooler. I have two antique garden tractors and both see M1 20w50 M/C oil.
 
A jump-in question. if I may? I may be expunging a life-long misconception.

All the mower/lawn tractor oils which come up here are detergent oils, yes?
I've been using non-detergent 30W in my mower for a long time.
Have I been wrong this whole time? I have always changed it out in a timely manner.
 
A jump-in question. if I may? I may be expunging a life-long misconception.

All the mower/lawn tractor oils which come up here are detergent oils, yes?
I've been using non-detergent 30W in my mower for a long time.
Have I been wrong this whole time? I have always changed it out in a timely manner.
ND oils lack pretty much everything an internal combustion engine needs. Some ancient splash lube engines called for non-detergent but that was back when ND oils were made with anti-wear, anti-rust, etc. Modern splash lube engines work just fine with modern detergent oils. Keep in mind, I've ran old splash lube mowers on cooking oil for YEARS as an experiment.

ND in a pressure lube engine is pure insanity.
 
Right.
"You want the rings to load up for good compression...", was the way I heard it.
Got it, pressure washer pumps and air compressors are just driven tools which just need lube.

Newly acquired lawn tractor w 23hp Kawasaki gets recommended 15W-40 oil....obviously detergent.
I didn't back think it to the 40 year old Sensation. An hour mow and I'll change it to......15W-40?
 
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