stick with G52 in your tranny - here's why...

SUNRG

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If your transmission specifies G52 fluid I highly recommend sticking with it as opposed to changing it out for one of the popular/common replacement manual transmission fluids because the viscosity of G52 is much thinner:
Viscosity Comparison @ 100 C
10.6 = Redline MTL 70-80
13.8 = Amsoil MTG 75-90
15.2 = Motul Gear 300 75-90
15.6 = Redline MT-90 75-90
15.0 = Elf Tranself Synthese FE 75-90
16.7 = Motul MOTYLGEAR 75-90

6.3 = OEM G52 (part numbers G052726A2 / G05272601)
With just over 43,000 miles on my 2004 Golf TDI 5-speed I drained my manual transmission fluid, re-filled with Motul Gear 300, and I brought samples of both the used G52 and new Motul Gear 300 to my local CAT fluid analysis lab.

Since I had written on the G52 oil sample label 75w-90 the lab viscosity tested the sample twice - both times returning a V@100c of 6.4.

My thinking was that either the OEM oil sheared way down OR the OEM fluid started out much lighter than the expected 75w-90.

So, I went to my local dealer this morning, bought a liter of G52, then drove to my local CAT fluid analysis lab and watched as he tested its viscosity right in front of me.

The result: VOA viscosity of G52 = 6.3


OEM G52 did not shear down at all in 43,000 miles of use:
V@100c: New G52=6.3, G52 after 43,000 miles = 6.4
Additionally, in these crazy unseasonably warm temps the Motul Gear 300 shifts fine - but early yesterday morning when temps were in the mid 40s - the first few shifts with Motul Gear 300 were noticably more effortful than the G52 ever was - even at below 0 temps.


Point being that even though Motul Gear 300 has an outstandingly low pour point (flows to -60) - **the 75-90 viscosity of common gear / manual transmission oils is IMO not suitable for use in VW transmissions where G52 is specified.**


OEM G52: 43k UOA




Motul Gear 300: VOA (this is as expected from a 75w-90 oil)
 
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dieseldorf

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Cool, thanks for gathering the data...I wish we had the info for G50 which has been used for so many years in these cars. I suspect it's very thin as well.
 

Mike_M

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Black 2002 Jetta GLS
SUNRG said:
If your transmission specifies G52 fluid I highly recommend sticking with it as opposed to changing it out for one of the popular/common replacement manual transmission fluids because the viscosity of G52 is much thinner:
Viscosity Comparison @ 100 C
10.6 = Redline MTL 70-80
V@100c: New G52=6.3, G52 after 43,000 miles = 6.4
Interesting! I'd been considering Redline MTL...I'm wondering, though, in light of G52's lower viscosity, why fuel economy seems to improve when one switches to MTL?

Mike
 

SUNRG

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Mike_M said:
Interesting! I'd been considering Redline MTL...I'm wondering, though, in light of G52's lower viscosity, why fuel economy seems to improve when one switches to MTL?

Mike
i think that phenomena has primarily been observed in earlier TDIs - not the 2004+ tranny's specifying G52.

G50 and G51 are listed by Bentley as 75w-90, whereas after G52, on page 34-15 in my Bentley book, it states "Viscosity is not specified for either (G52) gear oil."

therefore, while G50 may be on the light side of the 75w-90, G52 is significantly lighter - no where near 75w-90.

cheers!
 

Mike_M

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SUNRG said:
i think that phenomena has primarily been observed in earlier TDIs - not the 2004+ tranny's specifying G52.

G50 and G51 are listed by Bentley as 75w-90, whereas after G52, on page 34-15 in my Bentley book, it states "Viscosity is not specified for either (G52) gear oil."

therefore, while G50 may be on the light side of the 75w-90, G52 is significantly lighter - no where near 75w-90.

cheers!
Ah...my apologies. I didn't know which tranny fluid was specified for which models (didn't check). Didn't know G52 was PDs only. Mine's a 2002 (non-PD), hence MTL is still an option? :D

Mike
 

dieseldorf

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I am pretty sure G52 is 75W per info from VW-AG. It's also dino-based oil.

:)
 

SUNRG

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with gear oils, the acceptable V@100c range of 75w-90 fluids is 13.5 to 23.9 (the beginning of the 140 range). however, the only number that really matters for this discussion is the 13.5 lower cSt limit for 75w-90 fluids.

i realize we don't ultra-analyze gear oils like we have motor oils, so to put this in SAE terms all the common 75w-90 fluids would be 40 weight motor oils (cSt range = 12.5 to 16.2).

the cSt range of 30 weight oils is 9.3 to 12.4, which G52 is well below...

the cSt range of 20 weight oils is 5.6 to 9.3, so with a VOA cSt of 6.3, G52 would barely qualify as a 20 weight motor oil.

while technically a light 20 weight - the CAT fluids analysis lab manager said he thinks G52 is a 10 weight, as does Blackstone Labs [check out this BITOG thread - link].

DDs link states "G52: Manual gearbox oil SAE 75W based on a conventional hydrocarbons." and this fits since in gear oils 75w (straight 75 or 75 being the upper number) cSt range is approximately 4.3 to 7.2 cSt.
 

SUNRG

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Mike_M said:
Ah...my apologies. I didn't know which tranny fluid was specified for which models (didn't check). Didn't know G52 was PDs only. Mine's a 2002 (non-PD), hence MTL is still an option? :D

Mike
yeah u could use MTL... i wonder if anyone has tried G52 in a pre-2004 VW?
 

david_594

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There is a synthetic G52 and a non synthetic G52. Which one did you have? Was it the one in the white bottle?
 

OdinsRageSS

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Nov 16, 2005
good to know! my stock fluid is gettin notchy. I loved MTL, it was the only fluid that wouldnt make my 90 suzuki sidekick grind into 2nd gear, and it wasnt impossible to get into gear on a cold morning!

G52 here i come, in an 04 PD
 

david_594

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I have G52 in my 2000 Jetta from the white plastic 1L bottle. And my tranny is rediculous notchy when it gets cold outside.
 

SUNRG

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OdinsRageSS said:
good to know! my stock fluid is gettin notchy. I loved MTL, it was the only fluid that wouldnt make my 90 suzuki sidekick grind into 2nd gear, and it wasnt impossible to get into gear on a cold morning!

G52 here i come, in an 04 PD
FWIW - i recently ordered an Air Lift kit from Summit Racing and they gave me a $20 credit toward my next order - but i couldn't find anything else they carried that i wanted until...

i realized they carry Redline MTL. so i basically ordered and will receive a couple liters for free. i'm going to put it in just to see how it feels. as a 70w-80 MTL is the closest of the "popular TDI club aftermarket gear lubes" to G52 in viscosity...

i'll report back soon.

cheers!
 

Mike_M

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SUNRG said:
yeah u could use MTL... i wonder if anyone has tried G52 in a pre-2004 VW?
Cool...thanks again. And good question...I wonder if anyone who has will read that and answer? :D

Mike
 

robnitro

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Wow, 6.3 cst! But then, if its a straight 75, it would thicken up a lot with lower temps and be notchy like david_594 experiences.

People were saying watch out with the pennzoil (aka GM) synchromesh. That has a visc at 100C of 9.08 cst. I don't get why VW went so thin. BTW, the 40C reading is probably more pertinent to normal driving as the tranny probably doesn't get so hot. Pennzoil synchromesh is 41.6cst @ 40C.
 

SUNRG

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first - i just threw that out there that this may be a straight 75, it could be a multigrade - i don't know. however...

robnitro said:
Wow, 6.3 cst! But then, if its a straight 75, it would thicken up a lot with lower temps and be notchy like david_594 experiences.
the above is not what i understand would be the case. multi-grade oils start with a light base oil and add viscosity improving (VI) additives so the oil will not thin too greatly when hot. a multi-grade 75 with VI additives, like a 75w-90, would test as a 90 at 100c (13.5+ cSt). a straight 75, without VI additives, would test as a 75 at 100c (approximately 4.3 to 7.2 cSt).

if G52 were a straight 90, then robnitro's theory that "it would thicken up a lot with lower temps and be notchy like david_594 experiences" could be accurate.

but, knowing what we know, i doubt david's cold tranny notchiness is a result of G52's viscosity. it could be that G52 is not the best choice for use in transmissions where G50 is specified or it could be, as tonglsi suggested, that possibly david's shift cables could use calibration.

DD - the G52 that is synthetic is NOT specified for use in our tranny's, it's a 2004+ 02M fluid. part number G052171A2.
 

Fix_Until_Broke

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G052171A2 is $25.35 per unit (liter?) on 1stvwparts.com
G052726A2 is $9.80 per unit
G05272601 not found

Are these different quantities of the same stuff (liters vs gal??) or are they different

Anyone know what the difference is in the 02M compared to the 02J and why they can run at ~1/2 the viscosity?
 

SUNRG

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G052726A2 is $9.80 per unit
G05272601 not found
both of these numbers are listed on the 1 liter bottle of G52 i have
 

david_594

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dieseldorf said:
Where does this come from :confused:
Bentley manual for the MK4, the most recent version with the PD motor in it I believe makes mention of a synthetic and non synthetic G52 gear oil. I will double check tommorow.
 

robnitro

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Hey SUNRG,
I meant it would be a straight 75, a straight 90 would test at 13.5+ at 100, not 6.3. So either it is a XXw-75, or a straight 75. Isn't the higher number the visc at 100C??? Didn't they test the G52 at a 75 weight viscosity at 100C?

So then, if it is a straight 75 (not even a 90) it would be thick like molasses at 0c, or so. Our trannies probably don't even hit 100C on normal driving conditions, so that may be why they use a 6-7 cst fluid at 100C. But then, a straight viscosity oil would be less prone to shearing, so maybe its a cheap way to make VW be able to run dino oil.

One thing that perplexes me, is the stories of how Specialty Formulations MTL-R does so well in our O2J trannies. Its a 75w90, with 14.5 or so at 100C. Maybe they run a huge VI, like the pennzoil syncromesh (which is at 190 or so VI).

Anyhow, the crazy VW price makes me go ugh about G52 and G50. I'll stick to Pennzoil Syncromesh (w/ more often changes), or Specialty Formulations MTL-R or MTL-P.


SUNRG said:
first - i just threw that out there that this may be a straight 75, it could be a multigrade - i don't know. however...



the above is not what i understand would be the case. multi-grade oils start with a light base oil and add viscosity improving (VI) additives so the oil will not thin too greatly when hot. a multi-grade 75 with VI additives, like a 75w-90, would test as a 90 at 100c (13.5+ cSt). a straight 75, without VI additives, would test as a 75 at 100c (approximately 4.3 to 7.2 cSt).

if G52 were a straight 90, then robnitro's theory that "it would thicken up a lot with lower temps and be notchy like david_594 experiences" could be accurate.

but, knowing what we know, i doubt david's cold tranny notchiness is a result of G52's viscosity. it could be that G52 is not the best choice for use in transmissions where G50 is specified or it could be, as tonglsi suggested, that possibly david's shift cables could use calibration.

DD - the G52 that is synthetic is NOT specified for use in our tranny's, it's a 2004+ 02M fluid. part number G052171A2.
 

david_594

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From the bentley manual:


Take it for what its worth. The stuff I used was the bottle on the right.
 

SUNRG

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So then, if it is a straight 75 (not even a 90) it would be thick like molasses at 0c, or so.
No. The SAE using seperate and arbitrary systems for classifying gear oil and motor oil viscosities makes this confusing though...

75w-90 roughly equates to 10w40

in motor oils, G52 may be a straight 10. or using multigrade terminology, a 10w-10. SAE 10 when cold, SAE 10 when hot - meaning it does thin when hot but as expected for a SAE 10 oil.

this is part of the confusion with SAEs arbitrary viscosity numbers.

don't take my word on this - buy a liter of G52 and a liter of your favorite 75w-90. stick samples of them both in the freezer and see a) if G52 becomes syrup and b) which sample appears / feels thinner or seems to flow more readily.

here's some more info on relative viscosities: link
 
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Dimitri16V

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My 01 Golf definitely does not have sysnthetic in the tranny, It gets very notchy in winter but the 04 is smooth. When I added up some oil in the 01, it stank like sulfur, only dino gear oil smell like that
i am planning on using MT-90 on both cars, I had used MTL on my 16v scirocco, that stuff was leaking out of everywhere but the tranny was very smooth.
 

Kiwi_ME

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The G52 is even thinner than an ATF such as Redline synthetic D4, which is listed on their website as 7.5 cst @ 100C.
 

AndyH

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Brilliant Rob!

I think we'll have to be careful about using the 'G52' label for our lube discussions, as there are G52 gear lubes and G52 automatic transmission fluids.

This info comes from the AMSOIL product lookup for an '05 Jetta TDI. This isn't AMSOIL's data, they get it from one of the auto aftermarket data houses. This is also the data that appears at the quick-lubes and garages that subscribe to these data services.

02J 75W-90 GL4 VW Part number G052 726 A2
02M 75W-90 GL4 VW Part number G052 171 A2
09A (automatic) VW Part number G052 990 A2
01M (automatic) VW Part number G052 162 (-A1) (-A2) clear yellow
09G (automatic) VW Part number G055 025 A2

Thanks to Rob, we know that G052 726 A2 is 6.3 cSt fluid, and definitely not 75W-90.

Viscosity Comparison @ 100 C


(Manual Tranny Fluids)
16.7 = Motul MOTYLGEAR 75-90
15.6 = Redline MT-90 75-90

15.2 = Mobil 1 Synthetic 75W-90
15.2 = Motul Gear 300 75-90
15.0 = Elf Tranself Synthese FE 75-90
14.9 = AMSOIL AGL 80W-90
13.8 = Amsoil MTG 75-90
10.6 = Redline MTL 70-80
9.6 = AMSOIL MTF Synchromesh Trans fluid (GM/Chrysler)

(Automatic Tranny Fluids - except for G052726A2, and Redline D4 dual-use)
8.3 = Honda CVT Fluid
7.6 = Mobil 1 Synthetic ATF
7.5 = AMSOIL Automatic transmission fluid ATF
7.5 = Redline D4 ATF Dexron III / Mercon / API GL-4
7.4 = Mobil 1 Synthetic Dexron/Mercon
7.2 = Redline Synthetic ATF Dexron II / Mercon
7.1 = Mobil 1 Synthetic Multi-vehicle ATF
7.1 = AMSOIL Ford type F auto trans fluid
6.3 = OEM G52 (part numbers G052726A2 / G05272601)

5.5-6 = Ford Mercon SP

The industry trend is toward lower viscosity fluids is engines, transmissions, and differentials to meet fuel mileage requirements. Since only about 12% of the energy from a gallon of fuel is left to turn the wheels, and 6% of that is eaten by aerodynamics, manufacturers are doing what they can to reduce some of the 1.5% transmission loss and 1.5% axle loss (differential) by reworking gearboxes and fluids. Mercon SP and Dexron VI are ‘state of the art’ in the US. I wouldn’t be surprised to find that G052726A2 is the state of the art in Europe.

For the folks running later model cars, the G052726A2 looks to be the best product currently available, as it has the lowest viscosity and presumably will protect the gears to at least a GL-4 level. For folks looking to squeeze more efficiency out of their late model transmission, there doesn’t appear to be much on the market that is lighter and also has GL-4. This might not be a problem, using ATF in our transmissions, as Ford, Mazda, and Saturn (at least) manual transmissions have been lubricated by standard dino Dexron III fluids for years.

The best bet for shifting and highest fuel mileage for us with earlier cars might be the G052726A2. Who wants to put the newer fluid in their earlier tranny and see if the fluid is up to the needs of the earlier hardware? Or, better yet, who want’s to pool money to get some of the fluid lab tested for cold flow, VI, and GL-4 performance? :) Or - who wants to try Mercon SP?

Andy
 
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