2000 VW Jetta gear oil - thicker or thinner?

[gregoron]

On my MK4 Jetta with 118k miles, should I go with thicker or thinner gear oil? I am using OEM G 060 762 A2 gear which I just filled in a year ago. Lately, I've been crunching first gear sometimes when upshifting from a stand still. Never happened before I replaced my oil.

I read in a VW forum that VW manual trannies have a floating primary shaft that's supposed to be stationary. But, when the oil is cold the secondary shaft moves the primary shaft inadvertently and thus causes gear crunching. Now, I should go thinner oil if this is the case but I still notice gear crunch at first gear even when the transmission has been warmed up already.

Any recommendations on gear oil?

 

[azsynthetic]

I have been running Red Line MTL in my 03 Golf for the past 290K miles with no problem whatsoever. I am planning to run a thinner oil for better mileage but I won't get to it until maybe after another 100K. So, my recommendation is Red Line MTL.

 

[scurvy]

I quite like the OEM fluids in mk4 vehicles. Either G060 or G070 would work well; they're pretty much exactly the same viscosity.

Realign your shifter linkage as well. Dieselgeek has a great video on YouTube showing exactly how to do it. Takes all of about 5 minutes flat.

 

[dparm]

The OEM VW manul trans fluid (typically Castrol TAF-X) is outstanding. The specifications are right up there with the high-end stuff like Motul Gear 300, though a lot of people swear it is the absolute champ for cold-weather shifting.

Problem is that they charge a fortune for it.

My recommendation is Motul Gear 300 (75w90 GL4 & GL5). Super-high viscosity index, ester base, and very stable even under race conditions. I ran it in my old Audi S4 and even on the track the transmission continued shifting beautifully.

 

[aquariuscsm]

Does your car spec a 75W90 GL4?

 

[gregoron]

Yes, it is spec'd for GL-4 75/90. I am actually running VW 060 for almost a year now.

I also want to know what's going on inside the transmission when 1st gear grinds from a stop. Is it because the input shaft is still spinning despite the clutch being depressed? If so, is my 1st gear synchro worn out? Should I try thickening my gear oil to provide some resistance to the input shaft?

Thanks.

 

[badtlc]

your VW MTF is already very thin. I wouldn't go any thinner than that. Redline MTL (70W-80) would be a step in the thicker direction if you wanted to try that.

 

[k1rod]

I tried Redline MTL in my Jetta and shifting became notchy in cold weather (and that is here in Arizona). And I too have that problem with grinding if I try to upshift too fast at too high an rpm. Think I may go back to the OEM oil.

 

[gregoron]

RL MTL is a little thinner than MT-90 - it's equivalent to 30 weight engine oil vs 40 weight for the MT-90.

The OEM G 060 I got from the dealer was from the VIN they pulled from my car. I think it's GL-5 oil which may not be good for my brass synchros. It may be too thin so the synchro is slipping and not catching.

I will drain it out and try RL MT-90 as this is GL-4. This transmission was originally designed for GL-4. I will post results after the change.

 

[badtlc]

Why go for the MT-90? That is a rather significant jump in viscosity. The MTL would still be a step up over your VW fluid.

 

[gregoron]

I've been reading this tech info

http://www.redlineoil.com/content/files/tech/MTL and MT-90 Tech Info.pdf

and other forums

http://www.myturbodiesel.com/1000q/a4/manual-transmission-gear-oil-change-Jetta-Golf.htm

and they say that MT-90 would be better for my synchros. I'm thinking, I'm not getting all my thin G 060 out of that box so the MT-90 I'll be putting in there will be thinned out anyways.

 

[badtlc]

You might also checkout TDIclub. Many over there have been big Redline MTL fans for years. The ones that used MT-90 complained about cold shifting, but if you are in hawaii, that likely isn't an issue.

Both are great fluids.

 

[gregoron]

Thanks Badtlc. I'll look into it. But I have a gut feeling thicker is better in this case.

Before I changed to to OEM, it was notchy to 2nd gear. It may have had the thicker OEM fluid in there prior to VW thinning out their gear oil.

After the thinner G060 OEM, it was notchy and grinding to 1st. I also noticed slight leaking/weaping from drain plug since. I wonder what is the viscosity of G060.

I would prefer notchy to grinding.

 

[antiqueshell]

It is CRITICAL that you ONLY use a GL-4 rated gear oil in your car.

DO NOT let someone sway you that using a GL-5 or even GL-4+ (labels that state GL-4 and GL-5) is acceptable for your vehicle. Even [censored] VW dealers are guilty of this.

READ YOUR VW OWNER'S MANUAL and FOLLOW THE RECOMMENDATIONS IN IT!!

 

[gregoron]

Thanks Antiqueshell. I intend to stick with what's spec'd which is GL-4 only. This is one case where I won't go OEM as VW and the dealers seem to have changed the spec on their new gear oil over the years.

Other than Redline and Motul, are there other GL-4 75/90 gear oils available? No GL-5 please.

 

[antiqueshell]

@gregoron:

It is VERY HARD to find this in the USA and Canada in an aftermarket product. It seems like a conspiracy of some sort, as you can READILY find PLENTY of 75w-90 GL-4 spec products from a number of major oil companies, like BP(Castrol), Mobil, Liqui Moly, Shell, Chevron, Valvoline, ect. in Europe and other parts of the world. LOL.

It's funny how the virtual marketing folks from Ashland, SOPUS, and others here on BITOG are strangely silent when it comes to helping their customers find a way to buy their GL-4 products here in the USA.

Here in the USA it seems like your best bet is CRC Sta-lube
85w-90 GL-4. Although the low viscosity number is high it should be no issue in a warm climate like yours. Many other VW owners use it as well, and report it works perfectly. CRC is a first tier company as well so you know the quality is good and they will stand behind their product.

 

[artificialist]

Originally Posted By: gregoron

Other than Redline and Motul, are there other GL-4 75/90 gear oils available? No GL-5 please.

Amsoil makes a GL-4 75w90 gear oil.

If you search this section some more, you might see some reviews of it.

 

[gregoron]

Thanks for the info.

I saw a gallon of CRC StaLube at Amazon for $30.

Redline MT-90 is going for $15/qt at Amazon, but it may not be ideal for hypoid gears. I don't think my Jetta has any hypoid gear as it's FWD. But, working the math makes the CRC a good buy.

For Amsoil, I may have to pay for shipping from the mainland, while Amazon offers free shipping.