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Drain & Fill VS flush

So on a well-maintained car that one knows, do people think that drain & fill for the radiator and the tranny (w/filter) is fine, or should one shell out the extra bucks for a flush. I no longer do my own work, but there is a cost difference.

If you want to keep your vehicle well maintained get the flush and fill for the radiator only. Drain and fill for the transmission is better because the filter is changed when the transmission pan is dropped. Transmission flushing has damaged a lot of transmission in the past because the wrong equipment was used and operated by clueless technicians. Always avoid “quickie” oil change or transmission fluid change shops.

The engine coolant system should be flushed, no question. You want to make sure that the coolant and system isn’t contaminated. Contamination in this system can ruin lots of things including heater core, water pump, thermostat, etc…

The transmission is a little different and it depends on the mileage and/or if you are having issues with the transmission. I would suggest that if the car is due for routine maintenance, is well maintained on all levels, and working properly: There is no harm in having a flush and filter done (by a mechanic or dealer). Fluid change alone is also acceptable.

With the coolant, I would drain and refill, unless the car has been neglected in terms of maintenance. If it hasn’t been done for a long time, I would flush with water, not a chemical flush.

With the transmission, I would not flush no matter what. If it has been neglected, I would have the pan dropped and the filter cleaned. If the transmission hasn’t been neglected, a drain and refill should be all this is necessary.

I believe in flushing the cooling system with hose water only, no chemicals. I would not recommend flushing the tranny at all, only drain + filter & refill.

Other than the cooling system, most other flush recommendations are designed to flush your wallet of unnecessary cash. This allows you to walk without a limp…the only real practical reason for most flushes.

So, to reiterate for those who can read, this car has been well-maintained. Changes in excess of manufacturer recommendations. From reading it, I think I will have the cooling system flushed next time, and the tranny “serviced”. thanks for the comments
2003 Toyota Avalon

Thanks for the feedback. Wow! The second one today.

melott, we can all read, but you aren’t the first person to use the phrase “well-maintained” and have that non-specific phrase taken with a grain of salt. For some people “well-maintained” means the oil has been changed. For others, it means something else. Don’t take it personally.

If you change the tranny fluid by just doing a pan drop, you’re vehicle will no longer be well maintained. That’s because only 30% of the old tranny fluid is removed and the rest is still held in the transmission. That’s like draining only 30% of the old engine oil, changing the filter and adding enough new oil to bring the level back up to the proper level. Not an oil change in my book. And remember, transmission fluid is just 10 weight oil with proper additives.

You might want to watch this.


That’s like draining only 30% of the old engine oil…

Not quite, IMHO. Motor oil gets more overall contamination than trans fluid, which gets only wear materials and heat damage.