Viscosity 10W-30 vs 5W-40

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My Kohler 22hp lawn tractor operates using 10W-30 HDEO with no plans to mow this coming season when the temperature drops to 32 F in the eastern US. I cannot use 5W-30 since it will be out of Kohler's viscosity ambient temperature range. Can I use 5W-40 for spring,summer,fall and get the viscosity characteristics of a 10W-30? What is downside of using a 15W-40?

Reference:
Elf viscosity chart
 
Use 5w40 year round. T6 is a winner and is great for severe service.
T6 5w40 IMHO has no negatives.
 
I have to ask, what do you mean by "get the viscosity characteristics of a 10w30" when referencing a 5w40? Because the answer to that is no. You will get the characteristics of a 5w40 from a 5w40, if you're seeking the level of protection or mft of 10w30 as a minimum then yes the 5w40 would provide that. If you have no plans to use the machine below freezing what's the problem with the 10w30 that you're already running?
 
I am under the impression that 10w-30 ambient temp range is within the 5w-40's ambient temp operation range based on the link provided. I want to use a synthetic like T6 but it is only a available in 5w-40 or 15W-40.
 
Last edited:
Originally Posted By: Patrick0525
What is downside of using a 15W-40?


None that I can think of. It's what I use in all my air cooled engines.

By the time it's cold enough to worry about it being "too thick" (not going to happen, anyway) you won't be cutting grass in PENN anymore....
 
A dino 10w-30 is all your engine will ever need in the temps you're going to operate in.
You'll want more (more of this, more of that), but your engine could not care less.
 
I use Rotella T6 5-40 Year round in my JD tractor. I mow and push snow. Works great in all temps. I have also used Mobil1 0W40 and that works well also.
 
Originally Posted By: Linctex
Originally Posted By: Patrick0525
What is downside of using a 15W-40?


None that I can think of. It's what I use in all my air cooled engines.

By the time it's cold enough to worry about it being "too thick" (not going to happen, anyway) you won't be cutting grass in PENN anymore....



Agreed- he may see a 1.5% to 3% fuel consumpton increase from the listings I have seen using a 15w40 over a 10w30
Citgo HDEO and others like Delo list specs like that
 
I email Kohler, and they don't recommend 5W-40 as a substitute for 10W-30? Why? I thought ambient 90 to 100F would be covered.
 
This B&S response to engine oil viscosity
Yes this different than Kohler's recommendation.

=======================================================
B&S
Small Engine Oil Type Recommendations:

Use SAE 30 in warmer temperatures of 40° F and higher (5° C and higher).
Use SAE 10W-30 for a varying temperature range of 0 to 100° F (-18 to 38° C), this grade of oil improves cold weather starting, but may increase
oil consumption at 80° F(27° C) or higher.
A synthetic oil SAE 5W-30 is the best for very cold temperatures of -20 to as high as 120° F (-30 to 40° C) providing the best protection at all
temperatures as well as improved starting with less oil consumption.
Use SAE 5W-30 for very cold temperatures of 40° F and below (5° C and below).
For continuous-use, such as commercial lawn cutting or pressure washing, use Vanguard 15W-50 Oil (temperatures from 20°F to 130°F).

Things to keep in mind when choosing lawn mower oil:

Use a high quality detergent oil classified "For Service SF, SG, SH, SJ" or higher.
Do not use special additives.
Synthetic oils are an acceptable oil at all temperatures. Use of synthetic oil does not alter required oil change intervals.
 
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