Gear oil and box running temps

[HarryMann]

Ever since I had my trans rebuilt (11 years ago) it has always been tough to get into second gear when cold. Even with the MT90 back then. I have tried Union 76 synthetic and regular dino oil. The past few years even third gear was scratchy when it was hot. I just switched to Lubrication Engineers 9919 75w90 synthetic for it's superior ring and pinion protection to better handle the new Ecotec engine. I noticed right away the shifting into all gears was smoother. It has not been very cold in the mornings lately but that first shift into second goes right in. The third gear shift is smooth when hot now also. I have been told by others that it runs 30 to 40 degrees cooler on long trips in a SVX powered Adventure Wagen driven at above limit speeds.

I can't wait to try it out in my Unimog. That is one beast that needs the best gear oil possible since the gears run on bronze bushings and not needle bearings.

Also would like to add that no matter what gear oil you use change it at least every two years. If you are near 200hp or more I would change it every year like I recommend for Porsche's and Ferrari's.

Just nicked thios straight from the Syncro yahoogroups goup, author John Wessels.

Just wondering if this 30 ~40 deg (presume F) temp drop just by changing a gear oil is likely, without the stuff being super puff the magic wagon's dream potion
NB. Note he says, I was told...

[toomanytoys]

I'll bring my data logger and we can chuck it on someones van (or mine).. I just havent had time to do it so far.. (never home )

[max and caddy]

did i do this?

[lhd]

I used Castrol in my old van because it was the only correct viscosity (80-90) that halfords had at the time and it was silky smooth. After a main seal failure I filled up with silkolene from GSF (75-90) and the shift was never the same, always clunking in first and sometimes second so I can well believe this.
The clunking never showed up until the winter but I'm positive it was due to this.
That was on my old 2WD by the way.
Rob.

[toomanytoys]

2wd has had comma SX75w90 in, improved the change no end.. 2 changes of oil in 12 years... (well, more like 7 as its not been used much last 5...
Syncro. Mainly Fuchs syn gear 75w90.. works a treat..

[silverbullet]

2wd has had comma SX75w90 in, improved the change no end.. 2 changes of oil in 12 years... (well, more like 7 as its not been used much last 5...
Syncro. Mainly Fuchs syn gear 75w90.. works a treat..

I did a quick change before the S.Germany run as I had no idea of the age of the trans oil. What came out was a bit bronzey-looking but not too bad and still smelled sweet (for gear oil) Refilled with Comma as above, shift might just be marginally better but the acid test is cooler weather i.e single figures deg.C overnight.

The funny thing was I could only get 3.5 litres in the SA trans before it overflowed and yes it was level...

A quick and easy test would be to get some of those self-adhesive temp. tags with a range scale. I wouldn't be surprised to see peak temps of over 150 *C on a long run in high summer. Remember that a syncro has significantly poorer airflow around the trans than a 2wd...

I might just get some from Think Auto: Mocal do them in three ranges, 40-71( for intercoolers?) 77-127 (water/oil?)and 132-182 (trans.oil?) all *C, about £2 each

[HarryMann]

I think Aidan will say they don't fully drain unless upended, due to incline baffle

[HarryMann]

The clunking never showed up until the winter but I'm positive it was due to this.

Probably not Rob, winter makes a big difference, and you had also put oil of a lower viscosity in, tending againt a slower change. In fact, it is only usually winter where slow changes into 2nd usually, are (were) found in a whole range of boxes..

There are plenty of exploits and work-arounds, the whole thing is gone into quite some detail in the Wiki BTW

https://club8090.co.uk/wiki/Ge ... reluctance

[GoldSyncro]

Just out of interest, has anyone used this;

http://interflon.co.uk/cgi-bin/online/storepro.php" onclick="window.open(this.href);return false;

[max and caddy]

I think Aidan will say they don't fully drain unless upended, due to incline baffle

He will, he also told Me not to upend because any muck inside will slowly be filtered thru the bearing on the input shaft...causing it to fail...top tip there from the man in the know

[silverbullet]

While chatting to the young chaps who built a certain W12 panel van recently, the subject of transmission oil temps and their influence on hp/torque ratings came up. One of the lads said that their research had thrown up that the VW 091transmission has an upper limit of circa 150 PS from a n/a petrol engine (TD's with massive low-rpm torque were not discussed) but with an external pump and oil cooler this could be safely increased to 300 PS.
Controlling oil temps and thereby maintaining oil film strength - to keep the bearing and tooth faces seperated - is the key.
This practice can be applied to most transmissions assuming they do not have a gross inherent design flaw that limits the input torque to the unit.
He then went on to mention something about better exhuast manifolds and quad turbos

[B.J]

so, is this the right stuff for my box and diffs then?

http://demonoils.co.uk/index.php/gear-t ... il-5l.html" onclick="window.open(this.href);return false;

[silverbullet]

No. That page states GL-4 and GL-5, in other words it's a GL-5 oil. Use the Comma SX which is the correct stuff, it's cheap enough! Only comes in 1l pots, so 4 bottles will do even for a syncro being refilled from dry.