6 Speed Manual - Gearbox oil

[Tony]

I've got an SLK320 manual and I'm wondering about the possibility of using differeent oil in the gearbox. Merecedes use the same oil as in their torque converters. The problem I find is that, in cold weather, the gear change - particularly first to second - can be very stiff. I suspect the use of a more normal synthetic gear oil would cure this. Does anyone know if this is a possibility, or can anyone suggest another solution.    

 

[altreed]

6 Speed Manual

My wife has a z3, it has only done 9k.  The z3 message board say that the gearboxes are stiff up to about 11k,

What mileage has your car got on it.  Maybe that is the same issue, it needs to be 'worn in'?

 

[Tony]

6 Speed Manual

It's only done 8k. The change is getting less stiff but it's still stiff from 1 to 2, and I don't think it's going to free off much more. I'm still wondering about putting different oil in it, but I can't seem to find out what oil is allowable. Mercedes don't mention the gear oil because it's "filled for life". I'm very dubious about this. I actually wonder who determines the servicing intervals for the various components - the engineering department or the marketing department. It seems that a lot of cars nowadays are having their oil change intervals extended radically, yet oil hasn't improved that much in recent years and the engines also haven't changed that much. Either we've been wasting money changing the oil too often or the current intervals are an attempt to make the servicing costs more attractive to buyers. Provided the car gets through the guarantee period why should the manufacturer care. 

(Edited by Tony at 8:06 am on Mar. 5, 2002)

 

[Andy]

6 Speed Manual

Hi

The latter part of your post is correct. The leasing companies are pushing for lower servicing costs. But as we all know, this will come at a cost and usually to the second owner or third.

As for the gear box oil. Mess with it at your peril. If a problem occurs at a later stage and MB carry out a oil check at HQ to say quallity check. They will throw out any good will claim. I think your being to impatient.

Leave well alone till at least 18k. If you use the example of the engines. These days they don't get run in till after 60k.

Regards

Andy @ www.mercedesservicing.com

 

[Tony]

6 Speed Manual

Thanks for the replies. The box is certainly improving gradually with use. I can see why the road reports tended to be critical of the gear change as they would obviously be driving a new (or at least very low mileage car).  Possibly Mercedes should think about this.

I'm still thinking about putting different oil in though. Some years ago, when I had an old MR2 MkII, the car came back from a big service with the gear change very different from the way it went in. It had become stiff and a bit baulky (very like the SLK). I eventually found out that they'd put auto oil in the box, which is allowed according to the service book. In fact there's a pretty wide range of oils that seem to be approved. I bought the best approved semi-synthetic oil I could find and got them to put this in, and the change was back to normal - very light and quick. I was fairly surprised that a change of oil could have such a big effect. So I might risk it on the SLK. (Andy's probably thinking I'm barking mad and he might be right). 

By the way, does anybody know why the manual has higher fuel consumption, according to manufacturer's figures, than the auto. This doesn't seem to make sense to me - particularly the touring figure. I can't see how an automatic can return better figures cruising down the motorway when the top gear ratio is the same.    

(Edited by Tony at 8:44 am on April 3, 2002)


(Edited by Tony at 9:08 am on April 3, 2002)

 

[Matt Crooke]

6 Speed Manual

TOny, on the last bit of your post, are you sure the top gear ratio's are the same? reason i mention is i used to have a (sorry) Sierra 2.0i Ghia auto, the revs in top (4th) were quite a bit lower than the 5 speed manual counterpart. Also Auto's these days tend to have tourque converter lockout on 3rd and 4th (and 5th if its used) to stop that familer" Clutch Slip" that you get in an auto when you accelerate. This basically makes motorway cruising in an auto in top gear the same as a manual..thus giving you almost identical cruising MPG figures.

 

[Tony]

6 Speed Manual

The top gear ratios are not quite the same. The manual does 26.9mph/1000 rpm and the auto does 27.1, which is probably not significant. Mercedes figures for the SLK320 are (in litres/kilometre):
                           Manual                  Auto
Urban                   16.4                     15.1
Extra-urban            8.0                      7.7
Overall                  11.1                     10.4
CO2                       267                      250

So the auto's 6 or 7% better, which is strange. Also the CO2 figure is lower for the auto.

Another thing I don't understand is how this service indicator "Assyst" works. Mine started off showing about 10,000 miles to next service and has basically just tracked 10,000 minus the mileometer reading, within 2 or 3 hundred miles. Does anybody know what it uses to work out when the service is due ? I just like to understand things.