DEXOS certified Oil for a Kohler KT-740 / 7000 series mower?

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Oracledba

Joined
Feb 14, 2019
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Location
Parma, Oh USA
I have a "new" riding mower, coming up on 50hrs.
It had its 8hr oil change using conventional 10w-30
and now I want to switch it to full synthetic.

I am fortunate enough to have a RuralKing store nearby.
All RK branded Oil including DEXOS is $2.99/Qt or less[everyday pricing].
this includes:
full synthetic DEXOS 5w-30
full synthetic GF-5 10w-30
conventional 30w
[For those not near RK the AmazonBasics brand has all of the above for apx 75cents more]

I know DEXOS 5w-30 is best for my truck [using it 6 years] and I stockpile it.
But I have no idea what is best for my Kohler.
I will stock whatever I need to stock for Kohler longevity
just looking for advice on if DEXOS is the best product or GF-5 10w-30
or something else entirely.
I kept prior lawntractor working perfect for 15+ years ~50hrs/yr, Sold it for new hotness.
This lgt48dxl is my new hotness and looking to do right by it.
I am Ohio weather, minimal winter use.
I know manual mentions 10w-30 for my typical temperature usage.

Given the above, what is your advice?
 
Originally Posted by JayhawkRoy
My Kohler runs really well on 10W-30. It is now 16 years old and continues to do its job.


This!
thumbsup2.gif
 
I'm guessing since you're talking about RK oils the price point is also important. Personally I'd run a conventional HDEO 10w30 over a synthetic PCMO 5w30 or 10w30 all day every day in OPE. If you're talking a synthetic PCMO that's A3/B4 or has a HTHS of 3.5+ that's a different story. Rotella T4 10w30 is cheap enough, why look anywhere else?
 
Thanks everyone for your replies - this is helpful.
@FlyNavyP3 - I was talking about RK oils mostly because of a [misguided?] belief that
the numbers and letters of certification printed on the bottle meant something useful.
I presumed that I needed to concentrate more on those than the brand name of the bottle

My truck calls for dexos1 and RK oil has Dexos1 Gen2 printed on its label.
rightly or wrongly for last 6 years I have presumed that every and any
Dexos1 (and later Dexos1Gen2) oil would be be just as good for my truck
every other Dexos1 Gen2 because that certification meant I was in great territory.

It just so happens that RK has Dexos1 Gen2 for $3/qt [or $12/1.25Gal].
based on the above RK became my supplier for my truck's oil.
truck now has 135K on it via 5K oil change intervals.

While I might have to revisit the above decision,
having come to a decision on the truck -
I need now need to come to a decision on the Kohler.

My presumption was my choice was between
full syn AF-5 10w-30
or a dexos1gen2 5w-30
if the above presumption was correct I likely would source from RK for price and convenience.

I am not married to RK oil and what I don't know about oil can fill book.
So if my belief(s) are wrong which makes my decision faulty
then it would be great if those [such as yourself]
who know more than I can me guide to a [better] decision.
 
If the HTHS viscosity is available for the oils you are considering, simply choose the one with the highest value. If that spec is not available, then choose the 10w-30.
 
Originally Posted by Oracledba
Thanks everyone for your replies - this is helpful.
@FlyNavyP3 - I was talking about RK oils mostly because of a [misguided?] belief that
the numbers and letters of certification printed on the bottle meant something useful.
I presumed that I needed to concentrate more on those than the brand name of the bottle

My truck calls for dexos1 and RK oil has Dexos1 Gen2 printed on its label.
rightly or wrongly for last 6 years I have presumed that every and any
Dexos1 (and later Dexos1Gen2) oil would be be just as good for my truck
every other Dexos1 Gen2 because that certification meant I was in great territory.


It's true that the certifications mean something with regards to automotive applications. However, several people question the use of Resource Conserving automotive oils in air cooled OPE engines because of higher oil temps. On the other hand there are people on this board who run 5w30 or 10w30 even in warmer southern states. How hot would it be when you mow? Rotella T5 is a syn blend 10w30 with High Temp High Shear viscosity of 3.5 (vs 3.1 for typical Dexos 5w30). I have used it before in my 20 hp Kohler Courage with good results in summer temp up to 100 F.
 
Originally Posted by Oracledba
Thanks everyone for your replies - this is helpful.
@FlyNavyP3 - I was talking about RK oils mostly because of a [misguided?] belief that
the numbers and letters of certification printed on the bottle meant something useful.
I presumed that I needed to concentrate more on those than the brand name of the bottle

My truck calls for dexos1 and RK oil has Dexos1 Gen2 printed on its label.
rightly or wrongly for last 6 years I have presumed that every and any
Dexos1 (and later Dexos1Gen2) oil would be be just as good for my truck
every other Dexos1 Gen2 because that certification meant I was in great territory.

It just so happens that RK has Dexos1 Gen2 for $3/qt [or $12/1.25Gal].
based on the above RK became my supplier for my truck's oil.
truck now has 135K on it via 5K oil change intervals.

While I might have to revisit the above decision,
having come to a decision on the truck -
I need now need to come to a decision on the Kohler.

My presumption was my choice was between
full syn AF-5 10w-30
or a dexos1gen2 5w-30
if the above presumption was correct I likely would source from RK for price and convenience.

I am not married to RK oil and what I don't know about oil can fill book.
So if my belief(s) are wrong which makes my decision faulty
then it would be great if those [such as yourself]
who know more than I can me guide to a [better] decision.


I think you misunderstood my intent. I think RK Dexos1 oil is absolutely suitable for your truck. I was basing that as a price point for mower oil as well. Otherwise in a full synthetic for the mower M1 10w30 high mileage is a great choice, but significantly more expensive than Rotella.

I'm one of the people who thinks OPE is better served by heavy for grade oils, easiest and least expensive way to accomplish that is HDEO. I'm running 15w40 in all of mine, Mostly because I purchased a bunch of it cheap, when it runs out I'll go back to a 10w30 HDEO.
 
@FlyNavyP3 no worries - "were good" thank you for your advice and info on what you do.
@carbon12 - I'm in northern Ohio, if we have a 2 week stretch of 90's my grass is dormant and i'm not mowing, if it is a random day of 90 and I need to mow, I'll shoot early morning or late evening when things are cooler. As for the metric High Temp Sheer Viscosity - I have no idea - not something I knew I should learn about.

No one thus far it talking anything about the additive packets and/or attributes of DEXOS
so I think I am hearing that should not be a concern/attribute for a decision on a twin cyl, air cooled Kohler engine.

What I think I am being told is for air cooled engines in non-winter applications
I should be more concerned about operation in heat and oils tolerance/behavior to it
and conversely in winter applications pay attention to the lower Viscosity number.
Engine longevity remains the my primary goal and winter hours for me are nearly non-existent.
So I guess I need learn a bit more on High Temp metrics.
Sounds like DEXOS is out of the running for me and its a decision between
full syn 10-30 or something else such as Rotella (that not a pasta correct?) or 15w40 / 10w30 HDEO

if others wish to "weigh in" and/or guide this decision that would be great
[btw - I am a newbie and blown away at the responsiveness of this forum - thank you]
 
I forgot about Mobil 1 High Mileage 10w30 as suggested above. Also has an HTHS of 3.5 cP I believe. More expensive but is full syn and Mobil usually has $12 rebate on 5 qts spring and fall
 
OP, correct. Rotella is a Shell brand of HDEO short for Heavy Duty Engine Oil. T4 is their conventional, T5 is synthetic blend, T6 is full synthetic. In my opinion I'd rather have a more robust HDEO in conventional than a passenger car synthetic. The demands of the small engine are more aligned with the HDEO demands than they are with Passenger car motor oil or PCMO.

Truthfully provided you keep the air cleaner serviced and the oil full and changed, any reputable oil should provide adequate service. But to me when HDEO is cheap and readily available, that's my go to. Do I necessarily need the extra protection, probably not. But I'd rather have it and not need it than need it and not have it.

As mentioned above if you want to run a synthetic, Mobil 1 High Mileage 10w30 also has a HTHS of 3.5 like a HDEO, but it is more expensive.
 
Originally Posted by Oracledba
What I think I am being told is for air cooled engines in non-winter applications
I should be more concerned about operation in heat and oils tolerance/behavior to it
Now you are catching on. The oil in your air cooled OPE is going to get much hotter than the oil in your car. SAE viscosity grades like 5w-30 or 10w-30 don't tell the whole story for this application; you need to look at the HTHS viscosity. Look at the following if you will:

Mobil 1 10w-30: HTHS 3.0
Mobil 1 EP 10w-30: HTHS 3.1
Mobil 1 HM 10w-30: HTHS 3.5

As you can see, there is a pretty significant difference between these three 10w-30 oils. If you are cost conscious, then any good HDEO 10w-30 should be suitable. If you prefer name brand synthetic, then the M1 10w-30 High Mileage looks pretty good. It's what I run in my lawn tractor.
 
@Astro_Guy Thank you for your Candor and information.

It seems to me that amazon item B07C5QWHN6 is a "rebranding"
of M1's HM 10w-30.

Does anyone have an opinion on if that is true?
 
There remains a ton about oil which I do not know and I am impressed that
there is a vast pool of people who have this much knowledge and this much passion about oil.
We had a ton of postings on this topic all within a 24hr cycle.
Chatting with y'all changed my direction and preconceptions.

Because of your education, neither oil I first suggested when opening this topic is going into my Kohler.

I am hearing that operation in the 90's is killer on oil within air cooled engines.
Another killer is operation where there is interference with air cooling
(such as cottonwood fuzz or clogged filters).

I am hearing that in air cooled engines one needs to have a lazer focus on HTHS.
I am hearing HTHS is easier to acquire in HDEO type oils
but can be acquired in certain full synthetics such as M1's HM 10w-30.

I know that for me, I am unlikely to work OPE when its colder than 38 or hotter than 88.
I also feel I do wish to swim in the full synthetic oil pool (bad metaphor intended).

Since my mower gets but a single 2 quart oil change a year
I feel the cost of a 5qt bottle is not too much of a concern.
An unknown is storage of 3 quarts in an opened container for 2+ years waiting to be consumed.
I think I can tightly cap and keep stored in a basement shelf where temps do not change all that much.

For the above reasons feel I am going with a 5qt jug of M1's HM 10w-30
My apologies to all readers currently doing a "Palm to Forehead" motion of a bad decision.

On a side note. if one believes Amazon to be a reputable company
and one believes its AmazonBasics brand a but rebranding of existing products
and one believes the strings/descriptions on an AmazonBasics brand package
are the same strings found on the source product
then a google search will show there just aren't that many choices of bottles
sporting the all four strings of:
"10w30" "full synthetic" "high mileage" "75000"
Lots of bottles have 3 but very few have all four.
Readers may take that for what they wish hear.

It will be a few weeks before I pull the trigger and get this "todo" task done.
so there remains plenty of time change the above decision.
If there is further education or passion which needs to occur
feel free to post it I am eager/willing to learn. - and thank you!
 
For what its worth, the engine manufacturers sell their own brand of 10W30, which are very good. They are heavy duty engine oils, similiar to diesel oil, and more robust than passenger car 10W30 or DEXOS.

I would not seek out a DEXOS oil.

I WOULD seek out a heavy duty engine oil 10W30.

Rotella, Delo, John Deere, Kohler, or Kawasaki 10W30 oil (ie, heavy duty engine oils) is what I would run.
 
A DEXOS 5w30 is going to be better than the cheapest PCMO 10w30 oil you can find. Both PCMO 5w30 and 10w30 tend to have about the same HTHS. So if it can run on cheap 10w30, DEXOS 5w30 will work just as well, if not better. There are plenty of OPE that have worse oils then DEXOS 5w30. But onto this HDEO recommendation, I believe its a good one. If you want a full synthetic HDEO, consider going 5w40. Easy to find and get a good price on. That what I did to my lawn mower. Since you mentioned RK brand, they probably would have something there. I did see this: https://www.ruralking.com/oil-hk-5w40-full-synthetic-1gal. While there are lack of details, my guess is it would HDEO.
 
@NH73 I had no idea full syn 5w-40 was even a thing.
if one assumes Warren Oil makes HarvestKing (no idea if true but hey lets go with it)
warrenoil.com has 5w40 full syn in their product line
Both have an HTHS of 3.9 both have the string "Diesel Engine Oil" in their name...

Lubriguard Full Synthetic 5W-40 CK-4/SN Heavy Duty Diesel Engine Oil
http://www.warrenoil.com/MSDS-Spec/...%20FS%205W-40%20CK-4%20SN%20HD%20DEO.pdf

Lubriguard Full Synthetic 5W-40 CJ-4 Diesel Engine Oil
http://www.warrenoil.com/MSDS-Spec/...ull%20Synthetic%205W-40%20CJ-4%20DEO.pdf

I must say you have me concerned looking at a "diesel" oil
for my kohler gasoline engine.
Do I have any business even looking at this oil?

As I said before, what I don't know about oil could fill a book
if some of this forum can comment on this idea please.
as thinks are now I have been "talked" into M1 HM 10w30
 
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