03’ Corolla LE

Getting my 03 Corolla maintenance next week and upon talking to my mechanic ( who’s shop works on Toyota’s & Lexus regularly) stayed a couple of things that were confusing to me.

  1. trans fluid~ I was always under the impression that a flush isn’t recommended for high mileage vehicles so I’ve always opted for the drain & fill. Well he stated flushes are completely fine and have no chance damaging seals. That contradicts most I’ve read on the topic. I’m fine w doing the just a D&Fill. Any thoughts?
  2. Also I was going to do a radiator flush but I casually told him I had one done 5 years ago. Well he said a radiator flush is on recommend every 100k miles…when everything I read is about every 30k. He said in the last 10 years or so the fluids are synthetic (radiator fluid synthetic??) which allow for greater miles between flushes…

Sorry to be so wordy and thanks for any reply’s.

Your first question generates a lot of debate around here. Personally, I like drain and fills if you do them every 30k or so. No, you won’t replace all the fluid, but that’s OK. Included with the drain and fill should be a pan drop and clean (if possible on your transmission - it’s not on some) and filter change (again, if possible).

My second choice (and I’m fine with doing it, but a lot of places don’t do it this way) is a “flush” in which they hook a big tank of transmission fluid up to your transmission pump inlet line, and use your transmission’s own pump to exchange the fluid. Doing it that way means your transmission isn’t subjected to anything that it isn’t subjected to with regular driving. The advantage to this way is that you replace almost all of the fluid in one go.

The third way, that I do not like at all, is to stick an input and an output hose into your transmission and use an external pump to force new fluid in and old fluid out. This method can, in theory anyway, cause problems if the pump is too powerful.

In all cases after a transmission flush you should check the dipstick and make sure the fluid is pink. If it’s dark brown or black, they didn’t perform the flush. You more often see this kind of stealing going on at chain stores like Jiffy Lube than at an independent local mechanic.

As for radiator flushing, 100,000 miles is kinda pushing it. You can get away with it if you test the coolant regularly after 30-50,000 miles and make sure there isn’t any rust in it, and that the additives haven’t broken down. But by the time you pay for the tests, you might as well just get the stupid thing flushed. For most drivers, 100,000 miles means around 8-10 years worth of driving. I like to do my coolant on roughly 5-year intervals.

  1. I prefer a drain and fill and if you’ve done that regularly, Wonderful! Keep it up!

  2. 5 years between radiator flushes sounds about right, even for modern fluids. Radiator fluid is a time-based thing more than mileage. You might be OK with longer intervals but why risk it?

If you keep this maintenance schedule up, the car should last for 3-400,000 miles!


On tranny flushes I’ve heard both ways from good mechanics. But on some vehicles like some Honda’s, the manual will specify to not flush due to the permanent filter.

A drain and fill is what I do on my 99 Corolla.I follow the manufacturer recommanded maintenance schedule. 275k miles on my car and never had a transmission failure.

That’s only if the transmission fluid has been serviced on a regular basis.

Automatic Transmission Fluid

  • Automatic Transmission Fluid — Use only Honda Genuine ATF DW-1 automatic transmission fluid. Do not mix with other transmission fluids. Using transmission fluids other than Honda Genuine ATF DW-1 may cause deterioration in transmission operation and durability that could result in damage to the transmission.
  • Replacement Frequency — Perform automatic transmission fluid changes only in accordance with each vehicle’s maintenance schedule and/or Maintenance Minder recommendations. Consult your Owner’s Manual for your vehicle’s specific maintenance information.
  • Additives — Your vehicle does not require any automatic transmission fluid additives. Additives may adversely affect the transmission performance and durability.
  • Transmission Flushing — If a vehicle is properly maintained, there is absolutely no benefit to flushing the transmission as a maintenance procedure. Use of additives, solvents, cleansers, or conditioners as part of a flush, or as a system enhancer, are not recommended or warranted by Honda, as they may adversely affect transmission durability, performance, and shift quality.

And there are serviceable filters filters on Honda transmissions.



Although the filter in the transmission is removable, it requires the transmission to be disassembled to replace it, so it is considered non serviceable. However, there is an inline filter hidden engineward of the radiator. It seems to be hard to even find a reference to it, but it’s there and available. Genuine Honda (25430-PLR-003) Transmission Filter https://www.amazon.com/dp/B00GI9NP0O/ref=cm_sw_r_cp_apa_i_RmwcDbWCZ3DY8