John Deere Hy Gard-hy viscocity

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Aug 24, 2007
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128
Location
MA, USA
I am dealing with a JD lawn tractor with a Tuff Torq K46 transaxle. It appears the factory fill is john Deere Hi Gard-Hi Viscocity. They now recommending Their own Oil which is Tuff Torq 187Q0899000 oil. I do not know what it is. They will not publish any info on it. However they confuse the matter by saying other Transaxles in the same K46 family had 10w-30 or synthetic 5w-50 as the factory fill. These are basically the same style transaxles. It may be easier to figure out what is the better value choice if I knew what these mystery oils are basically. I have done some searches on this board and did not find anything helpful. Maybe I am not spelling everything perfectly. Sometimes the search just does not seem to do anything.

I was just going to use 5w-50. From what I have read, people are assuming the Tuff Torq is 5w-50. But after some thinking I want to use what is the best for this situation. I have read some have used 15w-50 and seem very happy. I assume they do not use it in the cold months.

Is there a break down for the average person to understand what these two mystical oils from JD and Tuff Torq are? Even knowing for sure the SAE viscocities would be helpful. Are they both Synthetic or semi or other? Etc. Is there something special about them that differentiates them from a 5w-50 motor oil? Thanks in advance to those who know and are willing to share.
 
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Like you say, it's a TT K46. A transaxle that's been around forever. I'd use any good synthetic 15w40 through 20w50 in it. The 50wt variants are better for heavy usage or very high ambient temps.
 
I have zero experience with your K46, but am bored and did a bit of internet sleuthing as if I had to make this decision for myself.

The internet does "suggest" that the Tuff Torq. fluid is a synthetic 5W50.

For others, here's the Tuff Torq. chart showing their "special" fluid replacing the old OEM's of 10W30, Hygard, and 5W50:

Here's some JD literature suggesting that Hygard is a 10W30 with 60cst @ 40C, 9.4 cst @ 100C. 5w50 synthetic is generally about 130cst @ 40C, 20cst @ 100C. https://www.deere.com.au/assets/pdfs/common/parts-and-service/parts/aunz-hy-gard-brochure.pdf

Here's a slick (biased), well crafted Tuff Torq marketing brochure showing their "special" 5W50 out performing standard10w30 engine oil in their units: ....they push the concept that their product is engineered different than engine oil.

This at least sways me to think the heavier fluid is a better choice, so toss out 10W30 and HyGard. Whether the Tuff Torq. 5w50 is special compared to engine oil brands is questionable. I, personally would not move up to 15W50 and especially not 20W50 unless I was in a very hot climate.

My decision then would be about TuffTorq brand 5w50 vs. others. Cost difference is significant. OCI is 200-250 hours for severe conditions. Hmmmmmmm.
 
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It might help us to know what lawn tractor you're referring to, but honestly I doubt it will change the answer much. The only reason I say that is because sometimes, some models may have inherrent issues. But if the K46 trans is fairly stout, the reality is that lube choice probably won't matter in the least. UTH lubes sometimes need to be specific if they unit they are being used in has specific concerns for the wet clutches, or in a trans that has powershift trans (electro/hydraulic shuttle shift).

But in a lawn tractor, it's just a small sealed drive unit, and really is not a big deal.
 
I have zero experience with your K46, but am bored and did a bit of internet sleuthing as if I had to make this decision for myself.

The internet does "suggest" that the Tuff Torq. fluid is a synthetic 5W50.

For others, here's the Tuff Torq. chart showing their "special" fluid replacing the old OEM's of 10W30, Hygard, and 5W50:

Here's some JD literature suggesting that Hygard is a 10W30 with 60cst @ 40C, 9.4 cst @ 100C. 5w50 synthetic is generally about 130cst @ 40C, 20cst @ 100C. https://www.deere.com.au/assets/pdfs/common/parts-and-service/parts/aunz-hy-gard-brochure.pdf

Here's a slick (biased), well crafted Tuff Torq marketing brochure showing their "special" 5W50 out performing standard10w30 engine oil in their units: ....they push the concept that their product is engineered different than engine oil.

This at least sways me to think the heavier fluid is a better choice, so toss out 10W30 and HyGard. Whether the Tuff Torq. 5w50 is special compared to engine oil brands is questionable. I, personally would not move up to 15W50 and especially not 20W50 unless I was in a very hot climate.

My decision then would be about TuffTorq brand 5w50 vs. others. Cost difference is significant. OCI is 200-250 hours for severe conditions. Hmmmmmmm.
I came to the same conclusion. 5w-50 synthetic would be best for this situation.. This is a JD lawn tractor that did over 3200 hrs before having trouble with the trans slipping. From what I have researched that is pretty darn good for this K46 transaxle considering it was used to plow snow as well as dealing with some steep hills. The type of tractor does not really matter except for the fact that you have to pull the transaxle to change the oil. You can add drain plugs to the k46, which will help in changing the oil but you still have to pull it because you can not get to the fill plug. JD says you do not have to service it. The dealers do not want to service them. They want to sell you a new transaxle or a new tractor. In all fairness to Tuff Torque they will say this is a light duty transaxle and should be limitted to mowing on relatively flat terain and not pulling a lot of weight (rider plus trailer).
 
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