we waist our time on oil we should be

[blueranger]

we waist our time on oil we should be talking transmission fluid.

here we are driving mercedes benz with great engines and weak trannys.
and i believe one one these super atf's might help us.. does anyone have any suggestions... someone said redline works miracles...

[ACM]

Just did my tranny fluid change.
Used non-synthetic Castrol Dextron/Mercon III as suggested by Mercedes.

My idea is not to waste money on synthetic fluid but just buy a good brand ATF. However, changing the fluid every 30,000 miles is, in my opinion, more important that using an overpriced synthetic fluid.

My car is an 1988 300E.
If I had a newer model, say 2000 forwards, I would probably use a synthetic fluid and still change it every 30,000 miles.
ACM

[Mike Murrell]

Tip of the hat to ACM.

As pointed out by one participant here(jackd), synthetic is more profitable for the producers.

Plain ole oil and dexron changed on regular intervals will serve us well as it has for how many years?

[lee polowczuk]

I am not a synthetic oil user..it costs too much to change out more than 6 quarts every 3k miles.

However, since the transmission fluid stays in for 30k, the math is better..so I use mobil 1 in the transmission. I can't say the transmission works any better, but I am thinking that the synthetic keeps the temp a few degrees cooler.

We really don't seem to have transmission experts on this board. Come to think of it, any board

[230/8]

To each his own...I suppose it really depends on your driving habits and how much you want to protect your expensive engine and transmission. I learned years ago how fragile ATF can be when I towed a trailer with a 220S coupe on it for a few miles with a Chevy truck. I had just service the truck trans. After the tow I rechecked the ATF level and it was burned black. The ATF had overheated on the tow and was worthless. Quickly changed it and the trans seemed to be fine.

I think the synthetic is a good idea for transmissions, the numbers certainly pencil out better. The heat resistance of syn ATF is worth it in my book. As to engine oil, I also use M1 syn simply because I cannot afford unnecessary repairs.

The Ford Mercon V and GM Dexron III specs are very similar. The Ford spec is rated for a higher temperature so if your choose regular ATF, I'd get one certified for both Dexron III/Mercon V.

230/8

I am not an automatic transmission fan of any sort. I even have a manual in my 300E. I would not have bought one with an automatic.

That said, in order to understand how to keep an a/t alive you must understand what kills it. What kills it is HEAT! The normal operating temperature for ATF is about 170 degrees F. For every 10 degrees above that temperature the transmission fluid life is CUT IN HALF! In other words, if your normal atf change interval is 30,000 miles and your transmission fluid temp runs at 180 F instead of 170 F then you should be changing the fluid at 15,000 mile intervals. If the temp is 190 F then you should be changing it at 7,500 mile intervals and on and on.

Unless you are pulling a trailer in hot weather, or have other problems that cause overheating, you are probably not going above 170 F. Remember though, if you are running hotter engine temps it effects atf temp because the atf cooler is in the radiator.

For a/t it definitely pays to change it often, but in the case of an a/t, DON'T change it hot or you'll get burned.

Good luck,

[pchansen]

Wait a minute... My '97 S500 manual says it has a lifetime fill! Thery're right. The fluid will last exactly as long as the transmission! In my car's world, that means about 120K per transmission/oil change.
Actually, since this policy is so rediculus, by the time you buy one of these cars with 80 or 90 thousand miles on the meter, the fluid is well on it's way to oblivion. I change mine every 25K in hopes I can nurse it along until about 180K. (car has 101K now)