HT 740 with Transynd

[luvrbus]

C rated 15/40 for diesel engines are good the S rated 15/40 for gasoline not so good

[DoubleEagle]

C rated 15/40 for diesel engines are good the S rated 15/40 for gasoline not so good

I assume that you think the synthetic 15-40 oils (C-rated) are okay, but not worth the extra expense? The 740's like to run hot, and the thermal breakdown temperatures are a little higher for the synthetics, would the difference be worth it (performance wise) for those of us that want the very best for our 740's?

[luvrbus]

Synthetic oils are a waste of money in a 740 it is not going to extend the life of a 740 IMO,some say it will drop the temperature by 5* but I never saw it, only benefit is less oil changes on the newer World Transmissions   

[bevans6]

Basically Dexron III is the standard duty fluid, and Type C-4 fluid is the heavy duty fluid but some Dexron III carries the Type C-4 rating as well.  C-4 is usually a heavy duty diesel engine oil, and it has the C-4 approval on the label.   Dexron III is rated for cold start operation down to -22F.  OW-20 Type C-4 engine oil is rated to -31F for Arctic use.  15W40 engine oil is rated to 5F, if colder than that on a cold start pre-heat is required before range operations (basically that means putting it in gear and driving it). Preheat is either an external heater or running the engine at idle with the transmission in N for 20 minutes before putting it in a drive range.

So Dexron III is your standard duty wide temperature range do-all for everybody fluid, while Type C-4 is your heavy duty fluid with a smallish issue with pre-heat if you drive in cold temps every day.  I am going to look for Dexron III Type C-4 for my transmission, if and when I get that far.  It's a pretty red colour so that should add to the excitement of finding leaks.

Brian

[luvrbus]

I don't recall Allison ever using Dexron lll in the older 700,600 or 500 series it was always ll lot of options for fluid on the older Allisons and Dexron is 10w for colder climates

[Iceni John]

I don't recall Allison ever using Dexron lll in the older 700,600 or 500 series it was always ll lot of options for fluid on the older Allisons and Dexron is 10w for colder climates

Is Dexron III backwards-compatible with II?   Did III exist when these transmissions were being made?

John

[luvrbus]

Is Dexron III backwards-compatible with II?   Did III exist when these transmissions were being made?

John

The lll is supposed to be backwards compatible, the 740 was being phased out when the Dexron lll hit the self's in 93 or 94  ,the lll for awhile you could get the red or green I still have a couple of qts of the green.There so many options for approved fluids on the 740 it makes your head spin I used the CAT TO oil in mine for years

[HudsonMarine]

I picked up some Dextron III from Oreily's yesterday, and it has the C-4 rating on the label.
I am still considering the 15w40 switch though as it would make sense the heavier viscosity would increase performance on several levels.
I have no concern about low temperature issues as I plan to never be in cold climate. Even if that happened, just warm the thing up before driving it.

Also wondered about tractor hydraulic fluid designed for hydrostatic transmissions and wet brake/clutch applications?

Seems reading through the oodles of posts on this subject, there's MANY diferent opinions out there.

I can testify to a Chevrolet transmission that ran on orange soda once, long enough to go 30 miles home from a party (don't laugh, it was too dang cold to walk).

[TomC]

15W-40 makes a lot of sense in Allison transmissions. Considering I run 15W-40 in the generator, for power steering, if I change to 15W-40 in the transmission, then straight 40 would only be for the engine. If you have a 4 stroke engine, then you could have all the same oil for all. Good Luck, TomC

[DoubleEagle]

For people in colder areas, I wonder if 5-40 oil would be a good compromise. If 15-40 is okay down to 5*, then 5-40 should be okay below zero F., but only if Cliff approves.

[luvrbus]

For people in colder areas, I wonder if 5-40 oil would be a good compromise. If 15-40 is okay down to 5*, then 5-40 should be okay below zero F., but only if Cliff approves.

I am not approving nothing it's all personal preference on what people use but I do think synthetics are a waste of money in the older Allisons 

[sledhead]

I used this in my hd4060 and got if for $99 a 5 gal . pail so if you guys buy it in US $ that would only be $65 a pail + tax

http://lubricants.petro-canada.ca/resource/download.aspx?type=TechData&iproduct=996&language=en 

now I will have to change it again to try and get all the dex. 3 out

dave

[luvrbus]

I used this in my hd4060 and got if for $99 a 5 gal . pail so if you guys buy it in US $ that would only be $65 a pail + tax

http://lubricants.petro-canada.ca/resource/download.aspx?type=TechData&iproduct=996&language=en 

now I will have to change it again to try and get all the dex. 3 out

dave

Dave, I cannot find where that fluid meets the 295 specs or approved for your transmission you have more data than you posted you should be fine though the early World Transmissions used ATF Dexron lll 

[sledhead]

you are right they make it very hard to find but here it is

http://lubricants.petro-canada.com/documents/HD_Synthetic_Blend_ATF_OEM-E.pdf 

dave

[Oonrahnjay]

For people in colder areas, I wonder if 5-40 oil would be a good compromise. If 15-40 is okay down to 5*, then 5-40 should be okay below zero F., but only if Cliff approves. 

      Are there non-synthetic 5W-40 oils?  If I were going to use a synthetic transmission oil, I guess I'd just go ahead and use TransSynd.  There was a bit of discussion earlier in this thread, seems to me that regular 15W-40 petroleum multigrade C-rated oil is about as good as you can get, esp. for the money (unless your transmission requires synthetic, of course).