Technical Gear box oil choices

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Technical Gear box oil choices

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I am curious which gearbox oil to refill with!

The choices are:

EP 75W/80 (log book) which is mineral based I think.

EPX 80W/90 (halfords selector) which is also mineral based but thicker at lower and higher temps.

Castrol SMX-S (castrol site) fully synthetic, don't know of the grades.

I'd imagine the castrol is the most expensive, as its fullly synthetic rather than mineral, but is it better? If not should I get the 75/80 or 80/90 :confused:

I'm interested in opinions and actuall results people have gotten.

Cheers,

Kristian
 
I currently (for about three weeks) now use 75W90 GL4/GL5, which as I understand from the dutch label is half synthetic. My previous oil was 80W90 GL4, heck knows about its minarality/syntheticity. This one was not good because it was next to impossible to push in 1st without a full stop, especially when it was cold. With the new oil the 1st goes in like a charm (well almost), but I do have an occasional short grinding noise going from 2nd to 3rd and from 5th to 4th (this last thing only at very high speeds and very hot engine/box). But I know the box is not in the best condition and it has been taken apart recently. Thus, if your box is in good shape I would recommend 75W90 GL4/GL5, the gears that do work, work very smooth, but I am yet to find out how this behaves in winter. Also, I will be sorting out the grinds with oil additives in not so distant future.

(Is your engine up and runnig that you are already digging into box issues?)

Cheers,

Woj
 
OK, cheers for your input :)

I have done some more reading and may just see how much tutela costs, as its fully synthetic, API 5 and rated for the box....awaiting more ideas though :)

It's not running yet, no, but when i was refitting the box, have the oil drained out over the floor and so it needs replacing. The box is my old box and so I know its good (y)

Kristian
 
I am not sure what those api things exactly stand for, but I think I remember reading somewhere that with this number it is not meant to go as high as possible - api 5 is not for regular road box usage (even heavy) if I recall correctly. I think it needs to be api 4 for our cars, or api 4/api 5 which satisfies both specs somehow. But wait for other to have their saying on this of course. I will try to dig out the article, but it is in a foreign language (to you that is ;)).
 
Well there is - a rough and quick translation from the article (in Polish http://www.off-road.pl/index.php?option=com_content&task=view&id=237&Itemid=2)

GL 4 - for manual gear boxes, where you have either high tourque, or high speed, but not the two at the same time

GL5 - best suited for high torque and high speed at the same time, example, for main diff mechanisms in 4x4 cars.

GL5s have twice as much "buttering" (really have no clue how to translate this, hope you will get the idea) additives compared to GL4.

And it says "GL5 is not necessairly better than GL4, it's just for a different purpose".

But my oil says both GL4 and GL5, which means one does not exclude the other.

/Woj
 
One more sentence I found that might be very useful: "Using the GL5 oil in boxes for which the producer recommends GL4 only may lead to chemical corrosion of some metals, for example, bronze synchronizers. An exception are oils satisfying both GL4 and GL5 specs."
 
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