Why does Allison not recommend using a power flush to change to transynd. My local transmission shop wants to use the power flush. Thoughts?
Terry
The Allison shop I used drained all they could, then put a bucket under the tranny, a tech disconnected a hose, asked me to start engine from rear start position and then hollered when he wanted me to shut it down, about 10 seconds. He said that removed 90 percent of the old fluid.
They then refilled the tranny.
Gary B
Local shop wants to make more $$ by doing a "power flush".
Why would you go against Allison recommendations?
Take it to an Allison dealer only.
or DIY
Good luck,
I would just remove filters and drain oil first from there then take out sump plug in the base and that will drain a lot more of the old oil. measure what comes out in total and then you know what to put back in. You must still do another drain around 10k so you have a pretty good idea that the concentration of the synthetic is pretty high compared to the old oil.
JohnH
Actually, per Allison, when switching from Dexron to Transynd or other approved synthetic fluid, their recommendation after the first synthetic change is to follow the recommended change interval for Dexron. After the second fluid change, THEN go to the longer interval for synthetic fluid.
Again there is a list of approved synthetic fluids on Allison's website. It does not have to be Transynd. I know Exxon/Mobil has one:
Mobil Delvac™ Synthetic ATF
and Amsoil "Torque Drive" although not on THEIR list it has same properties and a direct match. I took out the Transynd about 3 yrs ago then put in Torque Drive and not one problem, in fact it runs cooler by a few degrees if memory serves me right and definitly has not caused any problems. I even have a 100% guarantee on Tranny from Amsoil.
My reason for changing oil again after 10k was to get the complete swap over done as soon as possible, as why wait to do something that HAS to be done anyway??
john H
We think it practical to just drain and refill with Transynd, which is completely compatible with regular trans fluid. At this point the tranny is full with mostly synthetic and we just wait until we want to drain again in 3-4 years or so. Then we just drain & refill again with Transynd. Just don't think it important to remove hoses and run engine for a second which means that trans is running for a moment without fluid.
I would not do a power flush and I would not use AMSOIL. I would follow Allison's recommendations and use one of their approved fluids. My transmission is valuable enough that I want fluid in it that has been properly tested.
I would agree with stick to what Allison recommends. Also, when changing fluid, the torque converter holds a quantity
Of fluid that you can't drain, therefore you end up with a blend--- who knows what the effect of that is.
According to Allison, this is NOT a problem. That is exactly their recommended procedure-- drain using the drain plug, replace both filters and fill (do not power flush or attempt to drain converter).
David, in actual fact Amsoil did test it and reverse engineered it to exceed Castrols requirements AND I have a letter from them to doubly guarentee it against failure of any kind should the oil when tested by an independent analysis be the cause of the failure. As I said in a previuos posting this oil has been in tranny now around 3 yrs and NO problems have shown up. If it was causing any trouble it sure as heck would have shown up by now.
Remember this company started the synthetic oil business for autos etc when all the other ones siad it would not work. Well they sure jumped on the band wagon later when they realized they were missing out on a big market. They are a big sponsor in the racing field for all vehicles and actually do more testing than the "other ones" and all theor tests are finally done by "Independent sources" to verify what they found. New cars are now coming out of factory with synthetic because of the high heat and work required by engine. Castrol/Allison worked out a deal many years ago to corner the market and if you wanted to "Join them" you had to pay a large fee up front to be allowed the use of their Tes 295. Castrol was one of those companies that turned their nose up at Syn' at the beginning and said it was no good.!!!
Now they and others are have changed their tune, excuse me for laughing!!
As is seen in a lot of my posts I do not allways do what others do "pull out visa and pay" as I like to learn about the reason etc and after a lot of reading and facts came to the conclusion that this Torque Drive was a good oil for Allison. Time has proved out so far. All fluids in our coach are Amsoil. It runs great.
Your views are different and that is life.
JohnH
Aside from the available choices for AT fluids and back to the opening post.
Power Flushing any AT opens the door for valve body problems from contamination.
Fluid sampling is suggested unless you have obvious issues.
Leaks and overheating any AT are THE major issues. pc
Not sure what power flushing is, exactly, assume they are filtering existing fluid and circulating it?
Regarding the DIY flush, I've done this a few times. The procedure:
Drain ATF from tranny, replace filters.
Refill tranny with the same amount of new ATF that was drained.
Remove hose end that runs to cooler, put it in a bucket and observe as someone else cranks engine.
Watch cruddy old fluid run out from torque converter. When fluid exiting hose turns clear, turn engine off. Reconnect hose.
Refill tranny with ATF.
At no time is trans run without fluid. It seems to make sense to remove as much old fluid as possible rather than contaminating new with old. That said, there could be some other reason Allison recommends against it, some mechanical reason, room for error, profit from Transynd sales resulting from extra drain, who knows? Always safest to follow their recommendations. (edit) I have done this on several vehicles with no ill effects, but have not done it - yet - on the coach.
I've done this many many many many times on cars/trucks and never had a problem. It's the only way to get most of the old fluid out. Just changing the stuff in the pan is a waste of effort.
When FOT switched our coach to Transynd, they just drained and replaced the filters, then filled with Transynd. We went a short interval, then did another of the same procedure. After that, we were good for the extended period.
I worked on import autos for 45 years and of all the equipment I purchased over those years one stood out head and shoulders above the rest. It was a transmission flush machine made by "BG Products". Their machine had two hoses which hooked between the transmission cooler hose and the cooler coming from the tranny.. One coming from the tranny and the other to the inlet to the cooler. Inside the machine we placed 4 gallons of tranny fluid. In the "tank" was a bladder which separated the two halves of the bladder. When you started the engine the tranny pump would push old fluid in the empty side of the bladder and as it entered it would push new fluid into the system from the other side of the bladder. When all the old fluid was pushed out you would then be pushing new fluid out. Thus all new fluid. Most applications only held about 5 to 6 quarts so the rest of the new fluid was flushing. I would say that this was the most thorough flush possible and the safest. If you had bad clutches and the old fluid was full of fiber thus changing the viscosity, the flush could cause the tranny to slip. Ooops. But if the tranny is healthy, the flush would be the best way to change the fluid. The problem with a flush is the excessive amount of fluid needed. BG makes a synthetic fluid which is compatible with the Allison but I don't know what the current price is and I know they don't retail their products. Only service outlets had access. I'm running their fluid but only did the drain and refill with filter change.