I have a 1998 Honda Civic (manual transmission) with 108K miles. I have asked my mechanic to change my transmission oil on several occasions and each time he recommends that it is not a good idea. He reason being that when you drain the oil it dislodges a lot of particles that are stuck in the moving parts. The particles are from all the wear and tear that goes on in the transmission. Once the new oil is put in all the particles are suspended in the new oil and can cause damage to the transmission. I asked him if I should ever change the trans. oil and he said probably not. Can anyone offer a second opinion?
Does your car use Gear oil or something like Dexron?
If just Gear Oil (70w-90) then I’d worry about changing it after 200k miles. If Dexron which is much thinner…they no more then 50k miles.
The plug in the transmission housing is often magnetic to collect the particles worn off in use. This would tend to collect the dislodged particles after changing the fluid.
I would change the oil as the factory maintenance schedule recommends (my Accord manual says 90K miles). Any particles in suspension will be drained with the oil.
Does your mechanic recommend changing engine oil? Oil (engine, transmission, or differential) gets dirty and needs to be changed periodically.
I might start to question the competency of the mechanic. It might be time for a new mechanic. I don’t understand why a mechanic would suggest that, but I have never heard his rational, and based on everything I learned from years of experience and formal automotive education, I think he is up in the night.
I agree; you need to consider finding another mechanic. His logic is seriously flawed because there should be very particles at all floating around anyway. Any steel particles, if at all, would stick to the magnetic drain plug and any non-magnetic brass particles (synchronizer rings) will harm nothing.
JMHO, but I’m of the opinion that gear oil (hypoid) should be changed around the 100k miles mark. Additives can break down over time in any lubricant and hypoid oil is no different.
Some car makers used to recommend changing the hypoid oil initially around a 1000 miles or so but that has pretty much gone by the wayside as one of those things eliminated to make cars appear to be more maintenance free. (and it’s also unnecessary at a 1000 miles IMHO)
I have checked, and my old 98 Civic’s drain plug is not magnitized. (I sold the car but I still have the drain plug I replaced when I installed a drain valve.) As you will see in the thread you started in the “Second Opinion” forum of this site, the maintenance schedule in your owner’s manual says the transmission oil should be changed. Find a mechanic who is willing to read your owner’s manual if you aren’t going to read it. If you have lost your owner’s manual, buy a shop manual at an auto parts store. It will have a manintenance schedule.
Anybody will tell you anything. If there are particles, you see them in the oil that comes out of the transmission, rear axle housing, transfer case and anything that gets gear oil drained out of it. You see them all the time. New oil comes without particles. Nothing keeps things in suspension like gear oil. The big things, like broken gear teeth are always coming out with the old oil. They sink to the bottom. Check the vent at the top of the transmission. Honda used to have a rubber hose that went from the top of the transmission and would hang over the side. It would crack at the transmission and allow water to get in. That will trash a transmission a lot sooner than new fluid will. Let’s worry about real problems and forget the unsubstantiated nightmares of imaginitive mechanics.
If a manual transmission has enough particles in the oil to worry about then the transmission is on the way out anyway so why even change the oil.
Your mechanic is full of bunk, use your owners manual recommendation if any(some state check condition which is open ended). I changed mine at 100k with synthetic on my manual Civic. It noticeably shifted better after changing the fluid. I believe it uses 10w30 or something like that.