Thread: Gearbox Oil

Found this one (80W-90) but it is listed as both GL4 and GL5 according to the helpline!
I have a full product sheet coming.


Fuchs Australia - Product Details


Cheers, Mick.

Originally Posted by Warb

You might be thinking of the moly type additives that deposit a slippery coating on the metal? The Lucas product is "100% petroleum based" so no moly or teflon. As often is the case with these products, it gives no sensible explanation of how it is supposed to work, but the TDS shows a very high viscosity so I'm guessing it just thickens the oil.

Lucas has more than one product, the one I was thinking of came in a whitish bottle with I think an orangy single colour label and text, when you poured it out if you didnt shake it up really well first you got a light honey coloured oil come out first and then a whitish "goop" that looked a lot like loctite 567. Once it was all shaken up the colour was more like golden syrup.

Originally Posted by mick88

Found this one (80W-90) but it is listed as both GL4 and GL5 according to the helpline!
I have a full product sheet coming.

GL5 does include GL4. The issue is that GL4 and GL5 are "gear oil" specifications, rather than "gearbox oil". The specifications relate to gears turning against each other under load, but have nothing to do with synchromesh systems, and it is in synchromesh systems that the GL5 specification (possibly) starts to cause an issue.....

I have ordered 6, 1 Ltd bottles of Pen rite EP Mild for Gilbert, from Repco.
Listed as $19.95 per Lt, they said they would look after me.
Its coming with the next order, so no freight.
$12 per bottle.
Whitehillbilly

I've come to the conclusion that if you use modern thinner gear oils like Castrol Manual VMX-M API 75-80 GL4 or Caltex Easy Shift API 75-90 GL4 etc. in Series vehicles you can no longer rely on the old paper gaskets or felt smeared with grease as recommended in the workshop manuals. You also have to use modern sealants. Paper gaskets might work if you use your car for short trips only, but if you use it for touring in hot weather that thinner oil just seeps through every joint. .W.

It might not just be viscosity related, modern oils have more additives to make them cling to metal surfaces which could also make them more prone to wicking?

Additionally I have noticed that there is a massive variance in the thickness of "the same" paper gaskets from different sources. I have some drive flange gaskets that are very thin and made of a hard paper, and some that feel 5 or 10 times thicker and are far softer. On less than perfectly flat mating faces a thicker gasket will seal better, but if the gasket compresses with time the seal may fail and the fixings may lose torque... You pays your money and you takes your choice!

It is also worth remembering that we are talking about old machinery, there is a fair chance that the years have taken their toll and surfaces are no longer perfectly flat and true.

My approach is to use Blue Hylomar spray on the gasket, then torque up the fixings, retorque after 30 minutes or so, and then check again after a few days/weeks use.

I will say I've found that the Roamerdrive aluminium base plate for the transfer box (which comes with a thick gasket) seems to do a very good job of keeping the oil in!

I might have to try some of that Warb as my Roamerdrive sump plate started with the odd drip here and there and now seems to leave oil drips wherever I park the old girl. It appeared that the initial leaks were from the retaining bolts, so may have been weeping down the thread holes.
When I reseal it I will put some sealer on the threads as well.


Cheers, Mick.

My Roamerdrive plate is good, but now I have leak from (I think) the front output housing gasket. So it will come off and get a new gasket and output seal. It never ends.....

Genuine Blue Hylomar is good stuff, developed by Rolls Royce for jet engines. I've been using it for the last 30 years or so. I've only recently started using the aerosol version, mainly because it was the only genuine Hylomar I could get locally, but it seems equally good and easier to apply to gaskets. Having finally run out of the genuine "squeeze tube" product, a couple of weeks ago I purchased a tube of Permatex that was specifically labelled as equivalent to Blue Hylomar, because I couldn't find the genuine product locally. I haven't yet tried it, but there is a statement on the website of the Hylomar distributor in the USA that "Currently Permatex is NOT offering the true Hylomar material". Make of that what you will!