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veeracer
Active Member
USA
21 Posts |
 Posted - 07/03/2007 : 09:06:28 AM
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I am due for a tranny fluid change in my mt644 and I am considering going with a c4 fluid to replace the atf. I remember seeing previous posts about this and they seemed positive. Is this still the case? I do almost all highway driving.
Also, as I understand it, a lot of fluid remains in the converter and can't be drained. Is this mixing of c4 and atf ok? thanks |
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Brad Barker
Administrator
USA
874 Posts |
Posted - 07/05/2007 : 11:18:10 AM
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Quoted from the Allison MT service manual; "Hydraulic fluids used in the transmission are important influences on transmission reliability. DEXRON -II, and type C-4 (ATD approved SAE 10W or SAE 30) fluids are recommended. Type C-4 fluids are the only fluids approved for usee in off highway applications. Use type c-4 SAE 30W in all applications where the ambient temperature is consistently above 86 deg. F. (30 C). Some Dexron II fluids are also qualified as type C-4 fluids and may be used in off highway applications......Before using type C-4 fluids, consult the vehicle manufacturer to ensure that materials used in tubes, hosees, external filters, seals,etc., are compatible with C-4 fluids."
Oils should never be mixed. Flushing and refilling are recommended. Rig up a hose set up for flushing by removing the hoses, inlet and outlet from the trans cooler. Outlet into a clean bucket. Inlet into a clean container of the new fluid. Start the engine and run until clean new fluid comes from the outlet hose. |
Brad A. Barker |
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veeracer
Active Member
USA
21 Posts |
Posted - 07/05/2007 : 6:33:27 PM
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| Thanks for the info. I may have to reconsider and go with the if it ain't broke don't fix it philosophy. Determining hose compatability and flushing the system sounds like a lot of effort for something that may or may not improve reliability.The ATF is working fine,however it seems a higher viscosity oil(like delo 400 15-40) might provide better lubrication and longer life.? |
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wagonmaster
Top Member
USA
2298 Posts |
Posted - 07/30/2007 : 09:59:45 AM
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| Brad told you the "textbook" way to flush it, and he did a good job of it. A quick way that has worked for us is, remove the oil cooler lines at the trans and flush with compressed air. You could pour a little C4 in the line there to be sure, but we never did and we switched out the whole fleet of sevral hundred buses. Add the C4 and go for it. |
Joe
Land of the Free, because of the Brave! |
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IBTMech
Top Member
USA
973 Posts |
Posted - 07/30/2007 : 4:28:12 PM
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| I discussed this with our local DDA rep several years ago and due to our cold winters he recommended staying with Dexron ATF. |
If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years. |
Edited by - IBTMech on 07/30/2007 4:28:43 PM |
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wagonmaster
Top Member
USA
2298 Posts |
Posted - 07/31/2007 : 05:20:14 AM
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| Good decision. C4 isn't the best in cold winters! Since a cold day for us is 50* we don't really have issues with it. Besides, our newer units have the 5 year waranty which requires the synthetic fluid, and it isn't being swapped out for C4, and least not until the warranty period expires. |
Joe
Land of the Free, because of the Brave! |
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Topic |
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allison c4 or atf ?
