Auto transmission, change oil or leave it?

I have serviced many vehicles, and what you were told is only right in some cases. Many so-called oil change centers use a generic fluid that will change the characteristics intrinsic to some transmissions. Here is what to do, safely. READ your owner's manual first to determine the proper TYPE of fluid. In many cases on European models ( you did NOT indicate what year) a synthetic mineral oil is used, which means you need to purchase the fluid from either a competent foreign car parts store or from the BMW dealer. Get a new filter and pan gasket, as well, and purchase a can of CHLORINATED spray brake cleaner. Once the pan is dropped, spray the entire valve body (now visible) with the brake cleaner. This will dislodge minute paritcles of clutch material that gets stuck to it. Then, install the new filter and refill the trans. To be EXTRA sure, once this i done, THEN have the fluid exchanged for ALL new proper fluid. Remember that your converter and upper half of the trans still holds large amounts of old fluid. TO flush and fill is now the proper thing to do to prolong trans life. READ your owner's manual many times, especially the recommended fluid requirements. GOOD LUCK!!

Contrary to popular belief, the nice engineers who designed, tested, and established the maintenance schedule for your car really do have the best interest of your car in mind.

Read the owners booklet. Do what it says.

Yes, there are anecdotes of cars from the 60's running fine past 300,000 miles on a couple engine rebuilds that have never changed the ATF. But proper maintenance, at the proper time is the best way to identify small problems before they become big problems.

Especially for the careful backyard mechanic.

It is an easy process, it is a cheapish process, and the only harm that can possibly be done is if the wrong fluid is used, or if you allow dirt into the transmission, either when re-filling or into the pan.

In the last century, most factories recommended changing the fluid and filter every 20,000-30,000 miles. Today, with synthetic fluids, some recommend changing only every 100,000 miles. Check with the owners manual. At 130,000 miles, I would change it (including the torque converter fluid), and use the factory filter, with a high grade synthetic fluid (recommended by the factory). I also have heard that the high pressure of back flushing, on older transmissions, can damage the internal seals.

Some people who are having issues change it and then it quits on them.

If your tranny is working fine now, I would change the oil to keep it that way. Don't be surprised if the filter has fine metal particles on/in it, that is what it is there for. Even a new tranny will show some particles even with only a few miles. It is hard to get 100% of metal machining particles out prior to assembly and they will wash to the filter when filled and operated, this is normal.

Tranny oil will break down after about 100,000 miles and start to degrade and may start to accelerate wear on your plates and clutches.

Automatic transmission oil itself at best has a service life of 100,000 miles.

You will almost certainly notice an improvement in the drive quality, smoothness of gear changes and possibly fuel efficency too if you have a full flush change.

Look up an auto tranmission specialist that has a Wynns flush machine or similar for a near 100% change. Draining and refilling an auto transmission only changes about a quarter of the total volume of oil it holds.

Personally such a flush and change was one of the best things I ever did for my car.

It doesn't hurt to changed the transmission oil. Unlike engine oil, the transmission oil is sealed and won't get dirty. If it is clear light red, it will be fine. If it is dirty, some contamination exists. I would change it. Please measure exactly how much you drain out including the tranny cooler. And replace the same amount. Check level for a few days, make sure it is OK. To much and too little are not good for the car. Good luck.

I would do a drain and filter change. No flush.

People claim doing high mileage fluid change will kill the transmission. I think those people had problems coming in and then blame it on the fluid change. The properties of the ATF don't last forever. So if you don't, for sure it'll overheat and die on you.

Your flash car needs the transmission oil changing now.

Hi

The way I see it if the tranny isn't messed up go ahead and do it. But if it is messed up a fluid and filter change is not going to help. Preventative maintenance is a good thing

Here's a great article on pros and cons of changing high mileage transmission fluids

http://www.ricksfreeautorepairadvice.com/repair-to...