Mityvac, Tranny Fluid, Filter Question - PeachParts Mercedes-Benz Forum

shertex · #1 10-25-2008, 05:59 AM

I've had my tranny fluid and filter changed every 30,000 miles. If, instead, I evacuate the fluid with a Mityvac every 10K or so (and I'd do it twice each time to replace as much fluid as possible), how long could I go without changing the filter? Just trying to save a little money since I'm not a DIYer when it comes to the filter and pan.

Thanks.

Brian Carlton · #2 10-25-2008, 08:52 AM

People go 100K without changing the fluid and the filter. Sometimes they even get away with it.

Sometimes they don't.

shertex · #3 10-25-2008, 10:15 AM

Well, I'm not interested in rolling the dice. Just want to know, if I start with a clean tranny and do frequent fluid changes, how long could I reasonably go without changing the filter?

Brian Carlton · #4 10-25-2008, 10:19 AM

Quote:

Originally Posted by shertex

Well, I'm not interested in rolling the dice. Just want to know, if I start with a clean tranny and do frequent fluid changes, how long could I reasonably go without changing the filter?

I don't believe such data is available. You're attempting to operate the vehicle outside of the manufacturer's recommendations. Nobody can honestly tell you the ramifications of such a decision.

If you don't change the filter, and it reduces pressure, you'll notice problems with shifting and slipping clutches well before any damage occurs. If you pay attention to these symptoms, you can replace the filter at that time without any consequences.

sixto · #5 10-25-2008, 12:47 PM

I don't get how does replacing fluid twice in a session help anything.

My math says a savings of [$50 full service at 30K - $10 fluid change every 10K =] $20 every 30K miles. Is that what you figure?

Would you change engine oil every 1000 miles and not replace the filter?

Sixto
87 300D

shertex · #6 10-25-2008, 01:03 PM

Quote:

Originally Posted by sixto

I don't get how does replacing fluid twice in a session help anything.

My math says a savings of [$50 full service at 30K - $10 fluid change every 10K =] $20 every 30K miles. Is that what you figure?

Would you change engine oil every 1000 miles and not replace the filter?

Sixto
87 300D

Don't know what it's like where you are, but if I have a competent tech do it for me, I'm paying for an hour labor ($75 or more), plus the filter, plus the fluid. So I'm up around $120, assuming the torque converter is drained.

With my proposed method of two extractions, my expenditure of $15 or so removes over 60% of the old fluid (which won't be horribly dirty to start with)....or 75% if I do it three times...and I've saved around $100. And I guess every 10K might be too frequent. Whatever the interval, it's got to save some money.

From Brian Carlton's remarks, it seems the only downside would be the symptoms of a clogged filter....with no actual harm done.

The same economics wouldn't apply in the case of an oil change.

sixto · #7 10-25-2008, 01:54 PM

Not DIYing changes the economics but presents an alternative consideration. An investment in a set of ramps and some basic tools will pay for itself the first time you do a full service yourself

What's the history of your transmission? If it has 206K miles like the rest of the car, it's a fair gamble to cut back on fluid changes. I say that because there's a good chance it won't make it to 300K even if you service it religiously. The three catastrophic MB transmission failures I've experienced couldn't be directly attributed to improper fluid and filter service. On the other hand I don't know how many pre-200K failures were averted.

Sixto
87 300D

shertex · #8 10-25-2008, 03:00 PM

Quote:

Originally Posted by sixto

Not DIYing changes the economics but presents an alternative consideration. An investment in a set of ramps and some basic tools will pay for itself the first time you do a full service yourself

What's the history of your transmission? If it has 206K miles like the rest of the car, it's a fair gamble to cut back on fluid changes. I say that because there's a good chance it won't make it to 300K even if you service it religiously. The three catastrophic MB transmission failures I've experienced couldn't be directly attributed to improper fluid and filter service. On the other hand I don't know how many pre-200K failures were averted.

Sixto
87 300D

Original tranny, serviced every 30K miles. Only problem I had was a leaking reaction valve around 188K miles. Just a matter of a couple of O-rings; has worked perfectly ever since. And whenever the pan has been pulled the tech has commented on how good/clean things look.

My big decision may come if I get another leak....front pump seal or some such thing. Could get it re-sealed for about $1,000....or that could be throwing good money after bad.

sixto · #9 10-25-2008, 03:14 PM

Quote:

Originally Posted by shertex

Original tranny, serviced every 30K miles. Only problem I had was a leaking reaction valve around 188K miles. Just a matter of a couple of O-rings; has worked perfectly every since. And whenever the pan has been pulled the tech has commented on how good/clean things look.

That's precisely Brian's point - your regimen has served you well and should continue to do so. Why change things now?

Sixto
87 300D