Rover gearbox oil

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peterc
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Rover gearbox oil

Post by peterc »

Rover recommended several different oils for the SD1 gearbox throughout its life but finished with Castrol SMX which I have used quite happily for 15 years.
I thought it was time to perform a complete oil change rather than keep topping up but the Castrol SMX has disappeared from the market.
SMX was a semi synthetic and it would appear that the nearest equivalent is Syntrans Multivehicle which is fully synthetic.
Will it be safe to merely drain the semi synthetic out and refill with fully synthetic as I thought they shouldn't be mixed. There must be plenty of oil spread around throughout the gears and synchros.
Has anyone got any recommendations of other oils for a LT77 gearbox
Peter C
tasmin289
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Re: Rover gearbox oil

Post by tasmin289 »

Millers oils do an excellent range of oils. The TRX range includes a semi synthetic that would a direct swap for Castrol smx. If you go for fully synthetic you will need to remove a very high percentage of existing oil first. This will be difficult with the LT box as it has an internal pump and oilways as well as the oil that will cling to gears and casing etc. Paul.S
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Re: Rover gearbox oil

Post by DavidA »

There is a compromise required between the light oil needed for working the synchromesh and the heavier viscosity ideal for gears and bearings.
I've found Difflock Evolution 1 Fully Synthetic very good
Best Wishes DavidA
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peterc
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Re: Rover gearbox oil

Post by peterc »

Thanks guys.
I think I will continue to investigate the semi synthetic option and admit I hadn't considered Millers before.
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Migge
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Re: Rover gearbox oil

Post by Migge »

Posted it a few years ago I think. Sounds interesting. My LT77 is filled up with castrol and molyslip I'll see what happens in the future.

http://www.vintagemodelairplane.com/pag ... rbox01.pdf
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peterc
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Re: Rover gearbox oil

Post by peterc »

Thanks Migge
I'm happy to check how black the old oil is after having done only 14,000 miles before going the dramatic route of flushing and changing to fully synthetic. Maybe first step is to locate the Millers or equivalent. If the oil comes out too black then the flushing operation will need to be seriously considered.
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Re: Rover gearbox oil

Post by peterc »

In case any of you guys are still looking at this subject I have an update.
I emailed Castrol Technical requesting an SMX semi synthetic replacement and got the reply as follows.

Quote
Regarding recommending a semi synthetic - you didn’t ask that - the SMX was a full synthetic, and was replaced by Syntrans Multivehicle - and whoever gave you the information regarding removing traces of the oil is totally misinformed, as mineral, part and full synthetics used in modern automotive applications ( engines and gearboxes ) are all compatible, so no special flushing measures are required at all - just drain and refill as normal.

For the record SMX-S is fully synthetic and I was using SMX semi synthetic ( that's what it says on the bottle). Either way the good news is we can swop oil types without worrying about cleaning out the old oil.

Peter C
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Re: Rover gearbox oil

Post by Paul Blore »

Timely post Peter as I've got my gearbox out at the moment and I'm intending to replace the oil. In light of the above information, I'll now go for a full synthetic. :)

Thanks,
Paul
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Roger King
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Re: Rover gearbox oil

Post by Roger King »

Paul Blore wrote:Timely post Peter as I've got my gearbox out at the moment and I'm intending to replace the oil. In light of the above information, I'll now go for a full synthetic. :)

Thanks,
Paul
Paul, I think you have a toploader? When I started rebuilding toploaders some years back I was advised by Dan Williams ( http://www.toploadertransmissions.com/t ... rinfo.html ) not to use synthetics in a toploader. I don't remember the reason, but the same applied to my T10 last year - The guy who built it would not warrant it unless a GL4 (I think it was) oil was used. Nothing to do with seals, all to do with bushings and synchro rings. If you can wait until I'm back home at the end of the week I can tell you what was recommended.

edit - just found this from a guy I've used for parts:

'GL-5 has extra friction modifier additives which makes it more "slippery" than GL-4. For hypoid applications like rear end gears this is excellent. It's slippery enough that a lot of people that use it have found that they no longer have to add the extra modifier for their traction-loc rears. But for most transmissions that use blocking rings on the synchros, extra slippery is not a good thing.
Blocking rings act like brake shoes during a shift. They grab onto a gear a slow it down to match the speed of the gear shaft. Which makes a smooth shift. If the lube is too slippery, the blocking rings don't "grab" well enough which results in gear grinding (or "scraping") during shifts.'

another edit - I'm pretty sure this is what I'm using:

http://www.opieoils.co.uk/p-68916-mille ... 0w-90.aspx

as I said above, I can let you know for sure at the weekend.

Roger
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Re: Rover gearbox oil

Post by Karl »

If you have a toploader use 75W-90. As Roger says, the blocker rings don`t like synthetic, too slippery. It is an old design!
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