I have just got my split case gearbox ready to put back onto the pan and would like to know would it be ok to refill it with full synthetic oil or should I stick to mineral oil
Thanks

There was an interesting thread on the last forum about this subject.

Stay tuned!

I think that newer oils are actually quite bad for VW gearboxs as they attack the brass components within...do a search on shoptalk forums for the rundown.

Some EP (extreme pressure) additives attack certain brass alloy's in vw boxes. Be careful what oil you use, it's hard to know what's in them.

I find the safest option is to get an old oil bottle, clean it out real good. Then take it to a vw gearbox specialist who has been building vw gearboxes for years and get them to fill your empty container for you. They won't charge much cos they buy it in bulk, and what ever they buy has a good proven track record in vw boxes.

Just use the standard oil 90 grade.

yeah don't use GL5 rated gear oils in post 58 trannys as it is corrosive to the syncros, look for GL4 and make sure u use a hypoid oil.

Fuchs is the supplier to VW in Germany and we use Fuchs 75W90 gear oil

Thanks for the info so far but it is still a bit confusing

OK. As I understand it: The most common available oil is GL5 which is supposedly bad for VW gearboxes due to additives attacking brass/bronze alloys of the synchromesh. The older GL4 dosen't have these additives and is OK. Look in Repco, that's where I located GL4 stuff, Kmart etc. has only GL5 so just shop around it's out there......

yeah i have been having a hard time finding a GL4 rated Hypoid oil

I posted this yesterday but it disappeared. The type 1 gearboxes are straight ring and pinion style gears. Only the type 2 gearboxes are hypoid. So you only need the hypoid oil in the type 2 trans.

Hypoid oil is different to normal oil because the hypoid gears experience higher contact pressures and therefore need extreme pressure additives. But as I said before most EP additives eat the brass/bronze bits in the gearbox. So it is tricky to find an oil that will work as it is hard to tell from reading a bottle. That's why I take the approach of finding a proven oil and using it.

Also, don't get sucked into oil additive hype they have at car shows. Like the one where a guy pushes a metal bar on a spinning metal wheel. With normal oil it smokes, with the additive it doesn't. The test is an extreme pressure test, and the additive is an EP additive. Don't put EP additives into your engine. Your engine is designed not to have any extreme pressures. And your engine has more brass/bronze bits than your gearbox so you can imagine what happens.

Penrite Hypoid oil is GL 5 and copper alloy friendly.:thumb

What about Moreys oil additive.? I have used it in both the engine and gearbox of the 57 for about a year now. Has this one got the bronze / brass eating additives? :o

I dunno but I wouldn't use them. My tribology lecturer at Uni told us about the EP additives in those things being crap and wrecking engines.

He said how can a company sell an oil additive and say what effect it will have without knowing what chemicals are in the original oil. Made sense to me.

This is a pretty opld post... but i think it should be resurfaced... I'm kinda scared now coz i put in some Nulon gearbox additive into my split case... shold i drain the lot and fush it out a bit then use that GL4 oil?

This is a pretty opld post... but i think it should be resurfaced... I'm kinda scared now coz i put in some Nulon gearbox additive into my split case... shold i drain the lot and flush it out a bit then use that GL4 oil? What brands would one use that won't corrode the brass etc?

What not from the Quickie Mart Ned???

I think i'd prefer to use dead dino than bandanas....

anyone who prefers to use oil in their gearboxes too? what types are you running and have you heard anything about the corrosive effects of aditives? (both in the oil and aftermarket ones like Nulon and STP etc?)

Oval TOFU,
I have been using NULON in all My Vehicles for many years without any problems...
Castrol VMX transmission oils are GL4. in different grades.
I remember reading somewhere that the gearbox oils used in VWs WAS detrimental to Brass bushes etc - But it only attacked the brass if the gearbox was sitting for a long time.... and it was recommended to store VWs with NO oil in the Transaxle....

All additive manufactures say that the additives won't damage anything.... some don't do anything either... NULON seems to be good IMHO....

Doesn't the VW gearbox need a Hypoid oil as the Differential is included in the VW transaxle...
My Haynes manual says to use either :
GL5 SAE 75w-90 or 80w-90 Hypoid gear oil..
I did use GL5 75-85 in My VW Transaxle.

I have no idea what type of oil is in my gearbox, but I think it might be the same stuff it came from the factory with! :o

I'm not that worried about it, the manual says it doesn't require changing unless doing a gearbox overhaul, which it doesn't need.

I used Slick-50 in my past 1600 TP engine with no ill effects. But I believe that ordinary oil works fine... additives are just a additional cost..... better off spending that money on a slab or two!


:beerX48

Well, I have been using NULON in all My engines and gearboxes etc for many years. I have just stopped using NULON in My engines and now use Castrol Magnatech engine oil instead. It stops wear with out adding any additives...
Lee

just throwing in my 2 bobs worth but i have dodgy syncros etc in the 71 and i did and oil change refilled with 75 weight and used good old fashioned molybond in it and 1 year later its still a lot better than when i first looked at it and moly is compatible with oil and brass unlike the teflon based products

the diff isnt helical cut ie. hypoid, but the actual gears are aren't they? So wouldn't that require a hypoid oil? I'm using the run of the mill Mobil 80W-90 stuff from KFart and thats GL5....

**STOP PRESS**

I just rung Mobil on their help line and they had a listing for the VW trannys and they say that it the crap from KFart is too think and the EP 'could' corrode the brass/bronze alloys. I think that 'could' is pretty much a "yes" but they're just not allowed to say it outright....

He suggested another Mobil product call Mobil-lube GX-A 80W (GL4) [only comes in 20L!] or Mobile-Fluid 424. This is actually Ford's power steering fluid but is also used in 4X4's box's etc





so...USE GL4 RATED OIL AROUND THE 80W MARK.





I'm gonna use Penrite 80-85W and they state on the back that it doesn't corrode anything.... live and learn....and yo wonder why your syncro's in 2nd seem to always be dead....

The type 1 diff is a spiral-bevel gear-set. This means they are 90 degrees to each other, and the teeth are a spiral shape and not straight. The angle lets the load transfer from tooth pairs more smoothly and more quietly without backlash problems.

All forward gears are helical gears. The teeth are angled. Same load sharing as before.

Reverse gear is a straight cut gear. The teeth are straight across the gear. This makes the gear very weak as only 1 pair of teeth take the load at any one time. The transfer of load is also not smooth between teeth pairs, and makes the gearset whine. The advantage of a straight cut gear is it's very efficient. Helical gears produce a side thrust load which is a waste of power. That's why motorcycles and race-cars use straight cut gears.

A hypoid differential (used in type 2 gearboxes) is a spiral bevel gearset with the axis of the pinion and the axis of the ring gear offset from each other. This can make them even less efficient than a spiral-bevel, but not necessarily.

Luckily the vw engine and trans don't really care what additives you put in your oil. But later hi-tech motors will definitely not like teflon additives, as the teflon blocks the hydraulic lash adjusters (HLA). I wouldn't use additives.

Synthetic oils tend to be thinner and leak a lot easier. Stick with a mineral for the VW, it won't run any different with a synthetic, it will just leak easier.

MY V6 is a different animal. I ran my favorite mineral oil (as per workshop manual), and the HLA's were quite noisy. After speaking to MX6 forum guys, I found the V6 needs synthetic oil. So now I run Castrol R Synthetic 5-30W and it's very quiet.

Modern oils are designed to suit the demand of modern engines. The VW engine is ancient, and will run just as happily on ancient mineral oil.

I also spoke to Leon from Leons Motors. He has been building VW gearboxes for over 17yrs, so I asked him about the gearbox oils. He said he has never seen any evidence of any oil eating the brass/bronze bits in a gearbox.

So i can stick with the GL5 stuff? I respect your info and posts coz i know you're a chemical engineer or something the making... would 80W-90 be too thick? I dont think it would make that much of a difference in the tranny..

So what shoul di believe? GL5? GL4?


:puke

chemical engineer, nooooo!

Mechanical Engineer :thumb

I use GL5 stuff made for transaxles. It says on it, transaxle oil.

You won't get much variety in weight. I would have to check what I put in last.

Leon said he uses light weight synthetic gearbox oil in his trike, and even uses some slippery additives. But I think it costs him about $70 at oil change time. He said it gives good cold gear changes and good HP on the dyno, but it is expensive. He said the normal thicker oil seems fine if you don't want the expense of the synthetic, it just usually gives slightly notchy shifts when cold.

I don't mind the notchy shifts when cold, you should drive nice when it's cold anyway.

I'm intending to use some Penrite GL-4 80W-85 gear oil in my split tranny... the manual states i should use 90W in temps above freezing.... is this viscosity difference of '5' gonna be detrimental? Especialy seeing that summer is coming up? Or am i being pedantic coz the book is from the mid 60's and they were still bitching about using HD oils in the engine when all engine oils are pretty much HD now.... same goes for GB oils?

Cheers

tofe

[Edited on 14-9-2003 by oval TOFU]

Hmmm...... I hate stepping into oil threads, but here goes.
This info is related to 1.8L and 2L Kombi GB’s, and pretty sure most ‘70’s beetle GB’s. Not sure about older ones?
VW specified GL4 rated oil as that is what was available in the ‘70’s, as Wes say’s they are still fine to use. In the mid ‘80’s GL5 oils were introduced with new additives included. (Won’t bother with specifics). Some of these additives attacked brass and eroded them, which meant it attacked the syncromesh rings. When I questioned Shell these additives were removed by the ‘90’s (have heard it elsewhere also) from their oils.
So according to Shell technical, they still recommend using GL4 oil (because the book does) but their GL5 oils are fine to use. GL4 oil is also getting hard to track down. I don’t recommend one brand over another, it’s just what I use, and most brands will be equivalent, made to the same specs. (Please check for yourself)
As for synthetic or mineral oil, again both are fine to use. In general synthetics will last longer (don’t break down as easy) and are more stable at high temperatures than mineral oil (not a problem in VW GB’s). The comments on easier shifting is because of the ‘weight’ of the oil. With synthetics a wider range of weight is possible over mineral oils. VW recommend 80W90 oil for the GB (normal gear oil) Straight weights are not easily sourced these days anyway. With a synthetic the same gear oil is 75W90, which means it’s ‘thinner’ when it’s cold as Wes said which means changing is slightly easier when cold (more noticeable down south in winter than here in Brissy).
So the choice is yours!!
Andy:thumb