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Need Help: 08 ISF transmission service

16736 Views 10 Replies 10 Participants Last post by  Rudranshksingh
Hi everyone,

i just booked a service for my car, currently it is 88000KM, The dealership told me to do the "transmission service". it has two option:
1:drain and fill.
2: Flush

Do you guys know, do i need to do that?

thank you very much
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I would do a flush if I was you. It's an automatic transmission, after 50k (miles) I tend to change out the fluid.
I asked my dealer in houston about this and they said it was a world class sealed system with no service needed or no way to service. Is that bad info?
^ if I recall with this transmission it's a normal torque converter transmisison. I don't know why that would be considered a sealed unit. Can anyone elaborate?
I asked my dealer in houston about this and they said it was a world class sealed system with no service needed or no way to service. Is that bad info?
That is accurate/correct. After I purchased my '08 I was looking through the maintenance manual/guide and after first review went back to look specifically for any maintenance associated with the transmission as I didn't recall seeing any items listed. The following is a direct quote from the manual:

"The transfer case/transmission and transmission fluid are a completely sealed unit. Therefore, periodic checks and replacement of the transmission fluid are not required, and there is no dipstick on the transmission. Any repairs that require adding or replacing fluid should be performed by a qualified technician following procedures in Lexus service and repair publications."

That being said, I still had some questions myself about this statement and plan on asking for more details when I bring my car in for its next service visit.
In regards to which is better to have performed, the drain & refill or a complete system flush, provided either are actually an option for these understanding (and take that for what it's worth) is that it's generally best/preferred to perform a full system flush if/when you are doing so at regularly scheduled intervals. Essentially, the school of thought being that if no service, or irregular service, had been performed and the vehicle is "high mileage" there could be "gunk" in the system that is "holding things together" that if flushed out could reveal/produce other problems. For example, bad seals could be more likely or prone to leak after a full system flush. Whether you believe or agree with that or not is up to you but an interesting theory nonetheless. Again, that would typically only apply to a "high mileage" vehicle that had not been previously or properly maintained; in which case you may arguably want/expect to see other problems anyway. Food-for-thought :)
Hello! I'm not an expert in all this yet, but I'm interested in such questions. I esteem your opinions, I think it will come in handy.
Sealed means not consumer friendly. It is possible to DIY this. I have a 2014 Sienna with a “sealed” transmission and did the flush last month in my garage. The transmission has a fill and drain port. You just need to locate them. The drain will have a plastic standing pipe which sets the fluid level at a specific fluid temperature, normally 106F-115F. Once the fluid reaches that temp you top off the unit until fluid drains out and when it stops, you replace the drain plug. Its fairly easy except how to read the temp. I use an app called enginelink on my iphone with an OBD2 adapter called LeLink.

The flush is done by disconnecting the cooling line to the radiator. Turn on the engine long enough to pump out 2qts, then refill 2qts REPEAT until you have removed 12qts. The final fill is done when you are at 105* - 115*.

Drain plug: once you remove the drain plug, use a 5mm hex wrench and insert up drain, unscrew the plastic standing pipe and then drain out the trans fluid. Replace pipe and plug and add fluid. Flush trans. Via radiator hose. Top off by removing drain plug, allow trans to warm up, and add fluid until it drains out at temp. Replace drain and fill plugs. Done.

Sent from my iPad
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