# Gear oil change



## 20AE #1406 (Sep 20, 2004)

I decided to change the gear oil in my 99 Golf 4 Door, 5 speed, AEG motor at 157k miles. As expected, the gear oil coming out of the transmission was very black and had almost a water-like consistency. So, I replaced it with Mobil1 75W90. The car shifts smoother now and is noticeably more quiet than before. However, I was able to somehow make 1st and 2nd "crunch" once or twice when shifting quickly into gear. My questions are:

1. Was this caused by switching to a synthetic gear oil?
2. The problem goes away when I shift slower/normal, so is it my driving style?
3. Should I switch back to conventional 75W90?

The "crunching" use to happen once in a great while, but only shifting from 1st into 2nd gear with quicker shifting. I feel that if I drive the car for its intended purpose, a commuter, this problem might go away. Thoughts?


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## ps2375 (Aug 13, 2003)

Better asked/answered in the Manual Trans forum, but I'll add what I know. What rating of gear lube is called for in these trannys? I'm pretty sure the older 020's are GL4, these might be the same. That will be as important as the viscosity, as the syncros need the correct friction modifiers to do their job.


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## Jay-Bee (Sep 22, 2007)

There was a big thread on gear box oils on a different forum (maybe TDIclub?) It was linked on Audizine... anyway, it went to prove that the OEM filled fluid is not a conventional 75w90 weight oil.

I ran Motul Gear 300 75w90 in my MK4 2.0 and had no issues beside the first few shifts in the winter, I would actually usually skip 2nd gear, i had issues with it before the oil change, but it was noticeably better with the new stuff.

I'm trying to find out more as I want to do my trans and diff, but i'm in a VERY cold area of Canada for the next few winters and I don't want to cause any damage, with a heavy weight oil.

There are a couple threads on BITOG about VAG gear boxes too.


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## Glegor (Mar 31, 2008)

Jay-Bee said:


> There was a big thread on gear box oils on a different forum (maybe TDIclub?) It was linked on Audizine... anyway, it went to prove that the OEM filled fluid is not a conventional 75w90 weight oil.
> 
> I ran Motul Gear 300 75w90 in my MK4 2.0 and had no issues beside the first few shifts in the winter, I would actually usually skip 2nd gear, i had issues with it before the oil change, but it was noticeably better with the new stuff.
> 
> ...


i wonder if syncro-mesh fluid would work well in the 02A/J like it does in 020's in cold climates?

its nice and thin 

to the OP:

you really should have checked what type of fluid the trans called for before just throwing universal GL4/GL5 oil in there.. im almost positive that your shifting issue is caused by using the wrong oil.. GL5 oil is too slippery for our syncros so they CRUNCH when shifting, because the oil does not allow the syncro to slow the faster shaft and match their speeds..

find out what oil your trans is SUPPOSED to have in it, drain the stuff in it, and re-fill with the proper stuff..


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## tpc1031 (Jun 6, 2011)

*gear oil*

i just called vw and confirmed that the factory gear oil for my car which is a 8v 2.0 manual tranny is 75-90w SYNTHETIC.. drop that in your tranny you should be fine..


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## ps2375 (Aug 13, 2003)

GL4 or GL5?


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## Glegor (Mar 31, 2008)

ps2375 said:


> GL4 or GL5?


the GL4 or GL5 rating is VERY IMPORTANT!!


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## 20AE #1406 (Sep 20, 2004)

The web site states that their 75W90 gear oil is API GL-5.


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## 20AE #1406 (Sep 20, 2004)

The Mobil1 web site, that is.


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## harmankardon35 (Sep 16, 2009)

gl-4 only. buy the ford stuff (gl-4 manual transmission lube). or use redline fluid.


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## 20AE #1406 (Sep 20, 2004)

I'll buy two liters of VW gear oil just to keep my mind at ease. If that doesn't solve the issue, thankfully I bought an extended warranty that covers the transmission and the engine and it covers the internals of the transmission.


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## RawbiiD (Jul 13, 2011)

Chevron Deli 80W90, best gear oil your VW could use....and its not corrosive


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## 20AE #1406 (Sep 20, 2004)

Well, I switched over to the factory, VeeDub stuff yesterday and so far so good. After, maybe 100 miles on Mobil1, I drained it and looks light brown already! :screwy: The VeeDub stuff is much clearer than Mobil1 and has almost a watery consistency. :sly:


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## Glegor (Mar 31, 2008)

20AE #1406 said:


> Well, I switched over to the factory, VeeDub stuff yesterday and so far so good. After, maybe 100 miles on Mobil1, I drained it and looks light brown already! :screwy: The VeeDub stuff is much clearer than Mobil1 and has almost a watery consistency. :sly:


yea, i imagine its watery like syncromesh fluid.. its really clear and runny too..


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## 20AE #1406 (Sep 20, 2004)

Glegor said:


> yea, i imagine its watery like syncromesh fluid.. its really clear and runny too..


Well, I spoke too soon. Even with the factory stuff, I can still make it grind sometimes. Sigh... 

When the car has been driven for a while, at a stop and I put it into 1st gear, it grinds. 

When I'm at a stop and I go from neutral to 2nd then to 1st, no grinds. 

On top of that, when I go from 1st to 2nd when moving, it will grind with a quicker shift. If I'm going slow and I shift like my grandma, no grinds... :banghead:

I guess I have to granny shift 1st and 2nd gear from now on...


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## harmankardon35 (Sep 16, 2009)

20AE #1406 said:


> When the car has been driven for a while, at a stop and I put it into 1st gear, it grinds.


your clutch is dragging


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## 20AE #1406 (Sep 20, 2004)

harmankardon35 said:


> your clutch is dragging


Interesting. I'll check the clutch master and slave cylinders tomorrow for leaks. If one of the two, or both are bad, it would seem to me that 3rd, 4th and 5th gears should grind as well.


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## RawbiiD (Jul 13, 2011)

*oil*

Try some chevron delo 80w90. Its borate compound so it doesn't react with metals, making it gl4 or gl5 capable, its a high quality oil, realm stopped all crunching for me.


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## 20AE #1406 (Sep 20, 2004)

Interesting tid bit from the VW MANUAL TRANS OVERHAUL - TYPE 02J Article Text document for the 1999 Volkswagen Golf under the "Lubrication" section.

"Use synthetic gear oil (G50, SAE 75W/90). Capacity is 2.1 qts. (2.0L)."

I assume that the factory VW gear oil, which I'm using, is G50 75W/90, but what is "G50" and how does it compare to GL4 and GL5?


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## harmankardon35 (Sep 16, 2009)

g50 is a synthetic blend oil, heavily overpriced. You will probably like the performance redline mt-90

http://www.redlineoil.com/product.aspx?pid=46&pcid=7

actually made for vw transmissions and other imports requiring gl-4. 

gl-5 is a completely different can of worms, used for extreme conditions (differential gears, etc) so you want to avoid it.


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## 95jetta17 (Jan 21, 2008)

so your old oil came out black as in burnt did it smell burnt..i know in auto trans that burnt oil like that is a bad sign...


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## 20AE #1406 (Sep 20, 2004)

95jetta17 said:


> so your old oil came out black as in burnt did it smell burnt..i know in auto trans that burnt oil like that is a bad sign...


 It didn't smell burnt.


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