Transmission Fluids FAQ
     
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Some questions and answers about transmission fluids

What is this?

Transmission fluid is a slippery liquid that acts as a lubricant for all of the moving parts inside your transmission. In an automatic transmission, this fluid also serves as a “coolant” and a viscous fluid that transmits power from the engine to the transmission. A variety of fluids are used for different transmissions. Automatic transmissions use something called....are you ready for this....automatic transmission fluid (ATF). Manual transmissions use a variety of oils: regular motor oil, heavyweight hypoid gear oil or even automatic transmission fluid in some cases. Your owner’s manual will tell you what your transmission calls for.

Should I do this service when it’s recommended?

Yes, definitely, regardless of whether you have a manual or an automatic transmission.

Manual: Most manufacturers recommend that manual transmission fluid be changed every 30,000 to 60,000 miles. Under heavy-duty use, some manufacturers suggest changing transmission fluid every 15,000 miles.

Automatic: Service intervals for an automatic transmission vary from every 30,000 miles . . . to never. The typical service interval is 60,000 to 100,000 miles. Changing it more often does no harm.

Why do I have to do this?

Manual: In a manual transmission, the problem is not so much the fluid degradation, but rather fluid contamination. This contamination occurs over time as the synchronizers, bearings and gears in the transmission wear out. The resulting metal particles then float around in the lubricant. And we all know that oil with microscopic particles of metal in it does not lubricate as well as clean oil. So if these contaminants are not drained out, they will shorten the life of your transmission.

Automatic: Because more heat is generated in an automatic transmission, automatic transmission fluid actually degrades and breaks down with use. In addition, like in a manual transmission, automatic transmission fluid will also become contaminated with worn bits of the transmission. If these contaminants are not drained out, they will shorten the life of your transmission.

What happens if I don’t do this?

If you don’t change the transmission fluid on schedule, you’ll be lubricating your transmission with metal shavings and other contaminants. This will shorten the transmission’s life. The result could be a hefty boat payment to your mechanic. In other words, changing your transmission fluid at the correct interval is a good investment.

Can I do this myself?

Manual is a lot easier and should not cause too many problems! With automatic transmissions, I don’t recommend that you do this service yourself. Changing the transmission fluid is a disgusting, messy job! It’ll cost you a perfectly good set of clothes, in addition to the fluid itself. Besides, it’s not particularly expensive to have it done at a garage. Lots of shops now have a special transmission flushing machine that can replace all of the fluid in a transmission, as well as a separate lock-up torque converter, which removes fluid that you won’t be able to get at if you just drain the system using “gravity” at home. Finally, if you decide to change your transmission fluid at home, you’ll need to properly dispose of your old transmission oil when you’re done, which may be difficult, unless you pour it into your neighbor’s flower beds at night!

Is there any maintenance required between intervals?

Yes. It’s important to regularly check the transmission fluid level between service intervals. Letting your car run low on transmission fluid can cause the transmission to shift improperly or not at all. It also can harm the internal parts of your transmission, which will not be properly lubricated. Unfortunately, you may not hear any noises or have other clues that your transmission is low on fluid, until it’s too late. So it’s important to get it checked.

Here’s how you can check your transmission fluid level:

Manual: Checking the transmission fluid in a manual transmission can be difficult. A few thoughtful manufacturers have included a dipstick, but that’s the exception rather than the rule. If you own a car with a manual transmission, we suggest that you ask your mechanic to check the fluid level when your car is up on the lift during an oil change. It takes just a minute.

Automatic: If you own a car with an automatic transmission, your car will have a dipstick for this purpose. Be careful not to make the common mistake of confusing the transmission dipstick with the crankcase dipstick. For most cars, checking the automatic transmission fluid consists of pulling the transmission dipstick out while the engine is warmed up and running and with the transmission in park. I suggest that you check your owner’s manual, however, since some manufacturers may have a different procedure. Some models now dont have dipsticks and have to be checked at a dealer who uses a special tool to measure the level.

Of course, always check your fluid level if you notice a leak of any kind.


They really do need clean oil you know!

This is an article I had on CD....I don't know the source or author but it's a great essay

Most owner's manuals say it isn't necessary. Yeah, right. That's why transmission shops are making a fortune replacing burned out automatic transmissions.

For optimum protection, change the fluid and filter every 30,000 miles (unless you have a new vehicle that is filled with Dexron III ATF ( Auto Transmission Fluid ) which is supposed to be good for 100,000
miles).

WHY ATF WEARS OUT

An automatic transmission creates a lot of internal heat through friction: the friction of the fluid churning inside the torque converter, friction created when the clutch plates engage, and the normal friction created by gears and bearings carrying their loads.

It doesn't take long for the automatic transmission fluid (ATF) to heat up once the vehicle is in motion. Normal driving will raise fluid temperatures to 175 degrees F., which is the usual temperature range at which most fluids are designed to operate. If fluid temperatures can be held to 175 degrees F., ATF will last almost indefinitely, say up to 100,000 miles. But if the fluid temperature goes much higher, the life of the fluid begins to plummet. The problem is even normal driving can push fluid temperatures well
beyond safe limits. And once that happens, the trouble begins.

At elevated operating temperatures, ATF oxidizes, turns brown and takes on a smell like burnt toast. As heat destroys the fluid's lubricating qualities and friction characteristics, varnish begins to form on internal parts (such as the valve body) which interferes with the operation of the transmission. If the temperature gets above 250 degrees F., rubber seals begin to harden, which leads to leaks and pressure losses. At higher temperatures the transmission begins to slip, which only aggravates overheating even more. Eventually the clutches burn out and the transmission calls it quits. The only way to repair the damage now is with an overhaul -- a job which can easily run upwards of RM5000 on a late model front-wheel drive car or minivan.

As a rule of thumb, every 20 degree increase in operating temperature above 175 degrees F. cuts the life of the fluid in half!

At 195 degrees F., for instance, fluid life is reduced to 50,000 miles. At 220 degrees, which is commonly encountered in many transmissions, the fluid is only good for about 25,000 miles. At 240 degrees F., the fluid won't go much over 10,000 miles. Add another 20 degrees, and life expectancy drops to 5,000 miles. Go to 295 or  300 degrees F., and 1,000 to 1,500 miles is about all you'll get before the transmission burns up.

Worrying huh?

If you think this is propaganda put forth by the suppliers of ATF to sell more fluid, think again. According to the Automatic Transmission Rebuilders Association, 90% of ALL transmission failures are
caused by overheating. And most of these can be blamed on worn out fluid that should have been replaced. 

On most vehicles, the automatic transmission fluid is cooled by a small heat exchanger inside the bottom or end tank of the radiator. Hot ATF from the transmission circulates through a short loop of pipe and is thus "cooled." Cooling is a relative term here, however, because the radiator itself may be running at anywhere from 180 to 220 degrees F.!

Tests have shown that the typical original equipment oil cooler is marginal at best. ATF that enters the radiator  cooler at 300 degrees F. leaves at 240 to 270 degrees F., which is only a 10 to 20% drop in
temperature, and is nowhere good enough for extended fluid life.

Any number of things can push ATF temperatures beyond the system'sability to maintain safe limits: towing a  trailer, mountain driving, driving at sustained high speeds during hot weather, stop-and-go
driving in city traffic, "rocking" an automatic transmission from drive to reverse to free a tire from mud or snow, etc. Problems in the  cooling system itself such as a low coolant level, a defective cooling fan,
fan clutch, thermostat or water pump, an obstructed radiator, etc., will also diminish ATF cooling efficiency. In some cases, transmission overheating can even lead to engine coolant overheating! That's
why there's a good demand for auxiliary add-on transmission coolers.

AUXILIARY COOLING

An auxiliary transmission fluid cooler is easy to install and can substantially lower fluid operating temperatures. The plate/fin type cooler is somewhat more efficient than the tube and fin design, but
either can lower fluid temperatures anywhere from 80 to 140 degrees when installed in series with the stock unit. Typical cooling efficiencies run in the 35 to 50% range.

ATF FLUID TYPES

What kind of automatic transmission fluid should you use in your transmission? The type specified in your owner's manual or printed on the transmission dipstick.

CAUTION: Using the wrong type of fluid can affect the way the transmission shifts and feels. For eaxample, using Type F fluid in an application that calls for Dexron II may make the transmission shift too harshly. Using Dexron II in a transmission that requires Type F may allow the transmission to slip under heavy load, which can and probably will accelerate clutch wear.

CAUTION: Do not overfill the transmission. Too much fluid can cause the fluid to foam, which in turn can lead to erratic shifting, oil starvation and transmission damage. Too much fluid may also force ATF to leak past the  transmission seals.

 

logical sequence of troubleshooting....courtesy of Ozbrick.com

Click on Parts Diagram to go to Ozbrick.com

From all the discussions I have had (or read) with Volvo techs, tranny techs and on the brickboard, I have made up my mind regarding the sequence to follow when you see transmission problems. It seems like the most logical sequence towards fixing potential transmission problems is as follows:

Number one: Don't panic!!! Don't give -3000 US / -4500 AUD to Volvo or a tranny shop just yet! A lot of tranny shops will tell you that the transmission is completely shot when it may not necessarily be the case. It may be the case, but it may be due to bad fluid or PNP switch
 

Stage One - Information Gathering:

     
    • Check your transmission fluid and levels. If it smells burnt or is not a clean red colour then this may be indicative that it needs replacing. Wipe the dipstick on a white tissue/rag/paper to see the colour clearly. (My ATF looked a light brown this way, but when I flushed it out, it looked like a dark, opaque brown in the translucent white container.
    • Check your transmission fluid levels. Levels are checked when the car's engine is running and either/both when hot & cold (different levels on ATF dipstick for hot & cold).
    • Have a look under the battery area and see if the gear position selector switch has got crap all over it from the battery. This could indicate a PNP fault, as could loose connections that may be discernible with a "jiggle test".

Stage Two - Your personal transition to Mrs. or Mr. Fix-It

  • "ratchet clean" the gear position selector switch. To do this, move it rapidly between L and P about 15-20 times (with the engine off) to clean the contacts in the PNP. The switch is full of grease & three heavy duty contacts. It accumulates a lot of crap over time. Many report that it is most liable to become faulty in cold weather.
  • Completely flush ATF
  • Change gear position selector switch.
  • Get more than one expert opinion, just in case you might be throwing away heaps of bucks needlessly. You should seek the advice of at least one each of tranny shops, dealer, and independent Volvo specialist if you can find them. Then with the information found on this site and elsewhere, make an informed decision on your individual circumstance.
  • last resort: transmission overhaul/replacement. Ouch! 
     


Obviously this approach varies from the cheapest to the most expensive, in that order.

Of course, if you want to try the most expensive solution first for peace of mind, and it is your right to do it that way if you so wish.

Amazingly to me, some people that have passed by the Brickboard forum seem to have taken that attitude!

Me, I would prefer to spend four grand on another nice holiday to Phuket than pay the tranny shop proprietor to do the same!

Needless to say, I'll be flushing my ATF every year, or whenever it comes off the dipstick more brown than red, or if it smells like less than clean ATF...

                  That's my opinion, anyway.


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