Best transmission fluid for 450/452?

[JimbobTheSailor]

Hi everyone,

The slowness of the gearchange on my roadster is starting to get frustrating so I'm going to try and do all the things that might improve it: cleaning the actuator, replacing the gearbox oil, etc.

The only problem is that I can't work out which transmission fluid to use. Evilution lists 7 different types, Fq101.co.uk lists another, and my local Mercedes service centre recommends Castrol Manual BOT328.

I know that a lot of oils are compatible, but my main confusion comes from the fact that I thought Dexron VI fluids were supposed to superceded lower numbers, but no-one has mentioned Dexron VI.

Does anyone know for sure whether it matters which fluid I use out of all the ones I've been recommended?

Thanks for the help!

[smartsparky]

Re: Best transmission fluid for 450/452?

Come along to the Shepperton lunch tomorrow and we can talk about it then! (Amongst other options )

[JimbobTheSailor]

Re: Best transmission fluid for 450/452?

Thanks for the invite Smartsparky but unfortunately Shepperton is a little too far for me, even though it would be a fun drive.

Would you mind giving me your recommendation for transmission fluids?

[bilgladstone]

Re: Best transmission fluid for 450/452?

Smart has recommended (and nearly everyone here in Canada is using) Mobile1 ATF for the 450. Not sure about the 451.

Bil

[nikb]

Re: Best transmission fluid for 450/452?

Comma AQ3 transmission oil is a good alternative, cheaper too than mercs own or castrol, check with your local motor-factors they will give you an impartial view on which oil, as all they do is look it up in the book

[Evilution]

Re: Best transmission fluid for 450/452?

I know that a lot of oils are compatible, but my main confusion comes from the fact that I thought Dexron VI fluids were supposed to superceded lower numbers, but no-one has mentioned Dexron VI.

If you look at Dexron VI as being USB2.0 and Dexron III as USB1.1
You can use a USB2.0 drive in a USB1.1 port but you won't gain the advantages over the better USB2.0

You can use Dexron VI if you want, it'll probably cost a bit more than III but you won't notice any advantages.

[coolfart]

Re: Best transmission fluid for 450/452?

If you look at Dexron VI as being USB2.0 and Dexron III as USB1.1
You can use a USB2.0 drive in a USB1.1 port but you won't gain the advantages over the better USB2.0
.

You put transmission oil in your USB ports?????.......So does that help the PC run more smoothly???

Please do not take the above comment seriously......everyone knows USB's run better on Mobil 1

[Thrumbleux]

Re: Best transmission fluid for 450/452?

I know that a lot of oils are compatible, but my main confusion comes from the fact that I thought Dexron VI fluids were supposed to superceded lower numbers, but no-one has mentioned Dexron VI.

Does anyone know for sure whether it matters which fluid I use

It is confusing, not least of all as I don't think there is such a fluid as DEXRON VI! A DEXRON III, and MERCON V, yes, but no DEXRON VI that I know of. In any case DEXRON, MERCON aren't specs as such but classifications (that exist to indicate shift quality on an auto) and an oil in the classification is assigned a Qualification Number, typically a 5-7 digit number with a prefix letter such as D, G, F..
They are also classified into types, eg Type D, Type F.

An ATF in an auto box has 3 functions it must perform.
1) Like any other oil it must resist wear.
2) As a hydraulic oil to act on the pistons that occasion the gear changes, and transmit energy in the torque convertor/fluid coupling. For these requirements a large Viscosity Index is required as viscosity variation with temperature change is undesirable.
3) It must be compatible with the frictional elements (clutches and brakes).


In the smart, requirement #3 is redundant. Requirement #2 has some significance as there is a limited and constant force available to perform gear-changing from the electric motors.
Requirement # 1 is the most important by far.

So, forget the DEXRON, MERCON stuff and buy the best quality ATF you can find and if you can ascertain it's properties in relation to load bearing and/or wear resistance, so much the better. (Google them and look for Tech Data PDFs with Timken OK Load, FZG Wear Test, etc)

Don't assume Mobil is the best out there - it isn't.

[Evilution]

Re: Best transmission fluid for 450/452?

It is confusing, not least of all as I don't think there is such a fluid as DEXRON VI!

I must admit I took his word for it without checking but you are probably right, what happened to dexron 4 and 5?

[Thrumbleux]

Re: Best transmission fluid for 450/452?

what happened to dexron 4 and 5?

Just never went any further.
The DEXRON MERCON thing was devised years ago to give indication of the effect on the gear change the ATF would have. Some manufacturers wanted silky smooth changes, others wanted a pronounced kick as the box went up the gears.
Don't know what DEXRON stands for but MERCON is a contraction of manufacturers Mercury and Continental. It's an old American thing really.


Somewhere in smart literature it defines 450 and 452 gearbox oil by Type. Can't remember where I saw it though.

[Thrumbleux]

Re: Best transmission fluid for 450/452?

Just found this from a couple of years back.

ATF DEXRON D-21065 is what smart recommend

and found this on a net trawl
’ According to Esso, D21065 is a "qualification code" for Dextron II’’. Apparently when a type F ATF is used in manual boxes where D-21065 is recommended – swelling of the seals occurs'


Avoid Type F would be the advice.

[tolsen]

Re: Best transmission fluid for 450/452?

Comma AQ3 transmission oil is a good alternative, cheaper too than mercs own or castrol, check with your local motor-factors they will give you an impartial view on which oil, as all they do is look it up in the book

Comma specifies AQM for the Smart 450 transmission. A better oil is the new fully synthetic Comma MVATF.

[Thrumbleux]

Re: Best transmission fluid for 450/452?

Comma specifies AQM for the Smart 450 transmission. A better oil is the new fully synthetic Comma MVATF.

Would that be a newly developed oil with DSG boxes in mind?

[phingoc]

Re: Best transmission fluid for 450/452?

In norway, we use Castrol manual bot 328.. its good when the temperature drops to -30 C..