Fluids for Cummins 8.3 ISC and Allison Trans

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Jul 16, 2014
Hello all, This is my first post. Last summer I purchased my first motorhome a 99 Monaco Windsor with a Cummins 8.3 ISC 330HP and a Allison Trans. I changed the oil to Valvoline premium blue 15w/40 in the onan and the Cummins. I am about to change it again and have a analysis done on it. I was wondering if the lab could tell me if the tranny fluid is castrol transynd TES-295 or equivalent? I want to change the filters and if I can simply do that and top off with the transynd that would save a few hundred bucks in fluid. It has 85K miles. My understanding is transynd is pretty much good forever with testing. I would appreciate suggestions about the oil for the ISC and onan and the trans fluid. I drag race and run Amsoil 15/50 dominator and it's been fantastic, so many runs on this 540 ci motor and no lubrication failures ever. Very pleased with the Amsoil. I read good things about the Valvoline premium blue but that was a while back hopefully nothing has changed. Thanks for the help and info
It sounds like you have made a good choise on oil for both engines. Any of the major hedo oil's will do well. I really doubt that you trans came filled with tes295. Mine didn't though completly different applcation. The lab might be able tell you that, but wouldn't get my hopes up. A better idea imop would be to do a drain,fill and 5min run then drain and refill change external filter and let it go for 50k and change filter and top off. I know that's expensive but, at least you'll know what fluid you have in there. I would do some digging around on allison's web site. There is an listing for the transyend fluid that's approved. There's also a section on filter and oil change intervils based on type of service and series of tranny. You should be able to enter your seiral# and that will tell you everything you want to know.
I don't know that the lab can tell you for sure it's TES-295 licensed fluid. But they could perhaps get a signature from the spectro that would give an indication that the fluid is in line with general expectations. Since you're familiar with Amsoil, look at their ATD product and read about how they "clone" their fluid to the TES-295 product line. Generally, what you can glean from the UOA are two things: 1) the general health of the lube as a direct view 2) the general health of the tranny as an indirect view Get the UOA. Regardless if the fluid is a TES-295 or clone or something else, the info will tell you if it's worthy of continued use, or time to dump it. There are specific sub-forums on this site for UOAs for diesel oil, tranny fluid, etc. Please post up your results in the appropriate area when you get them so we can share and learn. BTW: welcome
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Allison yellow metal corrosion test is long .it is insanelly hard to meet .i would buy an oil that did pass it.if i recall isnt it 300 hour?
Op, welcome! congrats on your new toy, Tranny: what the service hx paperwork say? no tranny fluid is "lifetime". Fluids are cheap. As dnewton pointed out, testing might not reveal the brand of fluid, Engine: you are fine using any of the major label oils, remember, if in doubt, change!
I don't think the tranny had transynd from the factory but maybe the previous owner had switched sometime. I will likely just change it and see how the lab results come out.. Thanks everyone I will report back when I get the results because it will be Greek to me........
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