Post by
DTASFAB »
https://forums.nicoclub.com/dtasfab-u223076.html
Thu Aug 28, 2014 7:26 am
A drain/fill is less invasive to the overall operation of the system than a complete flush. The danger of incorrectly filling the fluid to the wrong level is a hazard that is present when doing a complete flush just as it's present when doing a drain/refill. I'm not sure what other failure points are present when doing a drain/refill.
Of course it's possible, even likely, that deteriorated fluid will cause damage to the CVT. But these transmissions are designed to, and despite their delicate nature, capable of, running efficiently on fluid that is not 100% new and crystal clear. When a brand new Rogue is purchased and driven off the dealer's lot for the first time, it's going to start taking on dirt and debris from the road almost immediately. Transmission fluid that has been driven a few thousand miles is not going to be as clean as it was when it was sitting on a shelf in a factory sealed bottle, but there's no need to change it right away.
I'm not necessarily saying the act of flushing the CVT is what can lead to damage. I don't think that's really a problem. The issue that I'd like to avoid is the possibility that tiny microscopic amounts of cleansing detergents could remain in the CVT after the flush, and over the course of tens of thousands of miles, the presence of this foreign substance can lead to failure.
Doing a flush with actual NS-2 fluid would avoid this problem, but it's simply not cost effective, nor is it necessary. I'm not sure how much fluid would be needed to conduct the flush, but let's say it's five quarts. That means you'd need five quarts to flush and then 10 more to leave in the transmission as the replacement fluid. If you're going to use 15 quarts, you might as well do three drain/refill cycles all within really short intervals and get most of the contaminants and deteriorated fluid out that way. You'd never get perfectly clean, brand new, crystal clear fluid into the system at any point, but it doesn't have to sparkle. It just has to be clean enough to last 20-25K until the next drain/refill.
As I emphasized previously, the key to doing only periodic drain/refills is that the procedure has to be done at a greater frequency than if you were to do a complete flush every 50-60K. In fact, if you try to stretch the original fluid from 50K to 60K, you'll probably run a higher risk of contaminated/deteriorated fluid damaging the system during those last 10,000 miles than if you simply did a drain/refill every 25K. The entire point to doing it more frequently is so that it never gets downright filthy enough to need a complete flush.