Best transmission fluid for 451?

[chieftmc]

Originally Posted by crepatas

I just changed the trasmission oil with Mobil1 75w90 (for $8.98 a quart). I got 3 quarts and the trasmission takes 2.5.

I did around ~60 miles with new oil and everything is great.

Straight, forward job I presume? Just like any other manual?

[mr_Cash]

Originally Posted by crepatas

I just changed the trasmission oil with Mobil1 75w90 (for $8.98 a quart). I got 3 quarts and the trasmission takes 2.5.

I did around ~60 miles with new oil and everything is great.

Where is the transmission fill & drain? Can it be overfilled?

Did you notice a better feel, or less noise, or (?), after the change?

I cant find a change interval for smart transmission oil, in the short 10,000 mile interval maintenance manual. Does smart company state anywhere, in any manual, the transmission oil is supposed to be changed, at some interval?

[xcrew229x]

I'm not sure I'm following the reasoning here on changing the trans lube. Whereas the engine has rather extreme conditions to deal with, many more "wear" parts, and much more chance of manufacturing debris, the trans is basically a sealed, non-invasive enviroment. I surely understand the normal wear of synchros, bearings, surfaces etc, but in just a short period of time? Anyone care to rationally comment?

[smartune]

Originally Posted by xcrew229x

I'm not sure I'm following the reasoning here on changing the trans lube. Whereas the engine has rather extreme conditions to deal with, many more "wear" parts, and much more chance of manufacturing debris, the trans is basically a sealed, non-invasive enviroment. I surely understand the normal wear of synchros, bearings, surfaces etc, but in just a short period of time? Anyone care to rationally comment?

Freshly machined parts are still "dirty" in a sense. They have rough surfaces and edges (at least when compared to parts that have been inside a transmission for some time)

Those surfaces wear smooth and foul the oil. New parts will also run hotter than those that have been in use, due to tighter tolerances.

Is it needed? Probably not.

But maybe its just worth the peace of mind, sort of a placebo effect?

With that being said, I'm changing my gear oil this weekend. Almost 10k miles on the car so I figure its time :P

-Dan

[artificial]

smart

[Okie Boy]

Originally Posted by whalepirot

Fred, thanks for your informative posts.

I am torn about the tranny lube, as my superb rear end guy asserts that a great gear oil, like Lucas, lubricates better than the synthetics. The only advantage for the synthetics over the dino oil is for extremely hot temperatures, which the Smart will not see.

Not true. The synthetics are slicker, more stable, and thinner for the same shear-strength. One has to be careful with some of the synthetic gear lubes becaus they are to slick and the syncronizers slip too much. Red Line 90W gear lube pours like 30W motor oil. Less friction better fuel econmy.

[Fredvon4]

There are two primary enemies to OIL be it conventional (Dino) OR synthetic

Heat
Crap n crud ( and all the chemical interactions they promote)

The term for both is oxidation and with oxidation comes loss of lubricity and a increase of abrasive matter...

New gear boxes are tight (we hope) and every meshing surface will do most all of it's life time wear in the first few hundred miles...while doing this the heat generated is higher then normal

There are no filters in this transmission
It IS vented to atmosphere
There is a rather small lube volume of 2.3 quarts and no appreciable cooling sump or large mass cases

Early change removes the contaminated over temped lube and replaces it with a new lube that should theoretically last the life of the car...

You might note that MB intends for you to leave the factory stuff in there for ever....

A thought...

Fredvon4's post are targeted to those of us who want our $17,000+ expenditure to last 10 or more years and not cost a fortune to maintain or repair...

[chieftmc]

Originally Posted by Fredvon4

There are two primary enemies to OIL be it conventional (Dino) OR synthetic

Heat
Crap n crud ( and all the chemical interactions they promote)................


A thought...

Fredvon4's post are targeted to those of us who want our $17,000+ expenditure to last 10 or more years and not cost a fortune to maintain or repair...

So Fredvon4, what kind of recommendation do you have for tranny oil change? 1k, 3k? I for one appreciate your expertise and am always willing to learn something new!

[Fredvon4]

I am coming up on 1000 this weekend... my local parts house only had 1 quart of 75W90 Mobile 1 gear lube... I am outside a small town and not willing to run 40MIles into the big city.... so I will patiently wait for the case the parts house guy orderd...that means next weekend at 1200+/- miles Farnsworth gets a dose of 2.4 quarts of new lube and probably every third~fourth year a fresh change of the stuff

There is no specific time to do the initial gear lube change but I think 1000 miles is reasonable to assume the box is pretty much worn in... I keep trying to remember to do MORE reverse gear work with her

[xcrew229x]

Farnsworth is a her?????