Oil recommendation for brush mower with Kawasaki 17 HP FH500V 4 stroke twin

Aug 31, 2020
North Stonington, CT, USA
Hi All,

I am trying to decide on what oil I should use in my walk behind brush mower. I have read many articles and forum threads on BITOG and got myself some oil I figured was a good choice (Shell Rotella T6 5W-40 Full Synthetic) however I still seem to be second guessing my choice. Seems that the more I read the more I realize how little I know so am looking for opinions.

The brush mower is an older DR Field with a Kawasaki 17 HP FH500V 4 stroke twin cylinder manufactured around 1997 or 1998. I have owned it since new and it only has about 300 hours total so I guess my usage is light/sporadic over the years. I have always maintained it regularly and changed oil and filters when needed etc and it does run well with no known problems. I live in Southeastern Connecticut so it gets reasonably cold in the winter here however it is a brush cutter so it is not used during the coldest months. I would say that the temperature range when I use it would be 35°F through 90°F.

The engine manual says to use API Service Classification : SF, SG, SH, or SJ and has the following chart...


I did read this thread about this particular oil dropping the API S rating however seems that a lot of people and deciding to continue to use it for outdoor equipment since it does have JASO MA and many consider it a good pick regardless.

My preference would be to just use it if it is a decent choice as that would save a trip to return/swap etc. On the other hand if it is a bad choice for some reason I would rather know now and avoid the mistake. Opinions and advice welcome and appreciated.

My Kawasaki V Twin zero turn mower uses less oil when I use a straight weight, just as the manual says. I'm in Florida cutting grass in the heat so I use a straight 40 weight.
My GTH2248XPC Husqvarna tractor has the Kawasaki FS641v 2 cyl. Turning a 48" three blade deck

627 +- Hours.

I'm using Shell Rotella 15-40 ( T5)Syn blend . No issues whatever.

As soon as my stash is gone im switching to the Shell Rotella T6 full synthetic 15-40.


Tom B.
T6 is an excellent choice and unless it has a catalytic converter (I suspect it doesn't), you don't need to worry about the lack of API S rating.
A few years back, Kawasaki back spec’d their small engines to 20W-50 for 32 degrees and up and 15W-50 for 23 degrees and up. With 10W-40 listed as recommended for most conditions -10 degrees and up. This was a very big change for many of their engines that came with tables recommending 10W-30. My FR730V runs significantly better with 15W-50 Mobil1 than with 5W-40 Rotella T6; no more blue smoke on startup and runs smoother at full throttle when warmed up.


I’ve been using Mobil 1, 5W-40 Turbo Diesel Truck in my 18HP Kawasaki V-twin powered garden tractor. It’s much the same engine, 18 years of abuse now, zero problems.

The diesel rated oils are fantastic for air cooled engines. Your choice of Rotella T6 is excellent.
In m zero turn with a Kaw engine I like using Delo 15/40. Another good choice is M1 10/30 HM but I do prefer Delo .
I use the 1o/30 M1 HM for generators and other single cylinder engines.
I have decided to use 5w40 in my Kawaski.
FYI based on the msds, the "best" Kawi Ktech "fully synthetic" oil seems to be mostly group 3 based. Note the predominant "C20-50 hydrotreated" component in the msds. Their other oils are just claimed to be synth blends. I think you can do better for less money.
Dino - 15w40 any brand however Delo has lots of Zinc!
SYN - M1 10w40, 15w50, M1 TDT5w40

Those old Kawis were great engines. Years ago I put 10w30, 15w40, and straight 30wt, all dino, in those engines. Probably would run using olive oil. I put many hours on them. 500's and 541's were solid.

Put M1 in the engine. I have had and seen great results from Kawis and M1 oil. Yes I do lean towards M1 because the highest hour Kawasaki engines I have worked on were fed M1 and oil level checked daily. Buy a 5qt jug of M1 10w40 for 22.99 and try it out.
Lots of opinions. I am amazed how passionate folks get over this topic.
I appreciate all the feedback, but saying "I did x for 15 years and never had a problem or had great results"
is kind of anecdotal. (Not saying it is not useful, but maybe we should elaborate explain what is meant by great results.

I think it is hard to objectively tell the difference objectively between 2 good products.
Maybe noise level is a thing. Perhaps a quieter running engine is a happy engine.
Temperature? A cooler running engine is probably a happier engine. How do we assess this?

No, or minimal oil consumption is probably a good thing. Easy to see when changing the oil...
A smoking engine is probably a bad thing,

No noticeable engine problems over a decade or 2 of use (such as a blown engine, loss of power, etc. )

Objectively assessed engine wear over a decade or 2 of use. could be useful;.
How many people know how to do that? Hard to do a teardown for a layman.

UOA is pretty easy and useful. I notice I see that less frequently for OPE threads than I see it for cars.
Lots of variables that are hard to control, but still, I think one of the more useful datapoints.

What else can you guys think of?
It sounds like you’ve done your research already and have chosen a good oil for your brush mower. Rotella T6 5W-40 is a decent choice.
I run a few older Kawasakis commercially and I use Pennzoil SAE 30. I get noticeably more consumption with multi grade oil. Be sure to check your dipstick before every start up.