LT77 Gearbox - What Oil?

[adam quantrill]

For me, Mobil 1 0W/40 plus Molyslip. Must have done about 30k miles on this.

No cold crunching even today when -2C start.

No hot crunching.

Not too pricey and a gallon gets you a refill "in stock".

[v8s4me]

stevoj said:

...Whichever way you go its is recommended to flush out after dropping the old oil with a mixture of engine oil and white spirit/paraffin.

What about diesel?

[bluezeeland]

v8s4me said:

stevoj said:

...Whichever way you go its is recommended to flush out after dropping the old oil with a mixture of engine oil and white spirit/paraffin.

What about diesel?

No, txs, rather like petrol.........

[TVRleigh_BBWR]

I use a rock oil 70-90 fully synth gear oil in the racer. and had no problems with gear changes, but the car always get's upto temp before use.

[MPO]

v8s4me said:

TV8 said:

..... Synchro crunch when very hot without it and not afterwards.

I get occasional synchro "notchiness" from 4th to 5th when very hot and high revs, so this is good to hear. Thanks.

Is it possible to drain the gearbox without a ramp, and am I going to need one of those big syringe things?

Ramps on front

drain and fill with one of these:-

http://www.screwfix.com/p/handy-parts-hp-162-oil-c...


MPO

[adam quantrill]

For filling I use 2m of clear PVC hose and a spare cap for the oil, with a hole drilled in and the hose a tight push fit.

Then you suspend the oil can above the car upside down and the hose end is in the gearbox fill hole, easy peasy.

[v8s4me]

I've bought one of the Screwfix enema kits and the Difflock is on order. There is a large hex-head plug at the bottom of the gearbox casing; can i use this to drain, or is this holding something important in place? It seems a bit big just to be a drain plug.

[carsy]

Yes that's the drain plug. Make sure you can get the filler plug off first though.

[v8s4me]

carsy said:

.... Make sure you can get the filler plug off first though.

It's putting up a fight!

[Number 7]

Should only be done up to 26 lbf ft - and its a taper fit.

[v8s4me]

Number 7 said:

Should only be done up to 26 lbf ft - and its a taper fit.

It seemed to be much tighter than that! I finally got it out with a 1/2" - 3/4" adapter and a big spanner. The drain plug was OK so now just wait for the oil to turn up.

Edited by v8s4me on Saturday 5th March 15:31

[adam quantrill]

That big drain plug makes a big mess when you remove it fully, best to put the filler plug back in now finger tight and it won't glug out so much.

[honestjohntoo]

v8s4me said:

now just wait for the oil to turn up.

Don't forget the radical flushing process:

• With the car on axle stands and the back wheels off the ground drain the box and re-fill it with a flushing mixture of 2:1 White Spirit and ATF.
• With the engine running at idle speed only, put the car through all the gears and let the drive train run off-load for 5 to 10 minutes.
• Upon draining the flushing mixture, be amazed at the filthy color and state of the drained fluid.
• Black as ebony with lots of sediment!
• Repeat the above with a clean batch of mixture to flush out the residues.
• Imagine the washing machine action inside the gearbox allowing the solvent component to reach into every recess.
• Refill with "Fully Synthetic Mobil 1 0W40" (My personal choice).
• Add recommended dose of Molyslip Gearbox Treatment, comes in a tube-like applicator available from Halfords, etc.

My LT77 has "Drain and Flush" as described every 4 years, and has run for 20 years without any of the (gross) original symptoms. Transformation was miraculous. A total pleasure to use.

Taken from my web page: HERE

[adam quantrill]

Yeah I used this flushing technique too. Removed a lot of crud - it gets in the oil pump galleries too.

Interesting about the 4-year repeat recommendation, what's you're average mileage in this time? As I guess I'll have to schedule a repeat performance sometime.

[ElvisWedgely]

I too think flushing the system out is a good idea and can only benefit the gearbox. I've never tried this, probably because I haven't had a wedge long enough. I might give it a go in the summer on my present wedge. Last time I used a fully synthetic mtf oil by Silverhook and it's been fine but if I flush it out, I might try the mobil 1 and mollyslip formula as sugested, seeing that it has a proven test record.

Tony. TCB.

[v8s4me]

honestjohntoo said:

Don't forget the radical flushing process:

• With the car on axle stands and the back wheels off the ground drain the box and re-fill it with a flushing mixture of 2:1 White Spirit and ATF.

Many thanks for the tips, very helpful. I don't have any ATF in the garage but I do have plenty of semi-synthetic 75W90. Can I use that to flush instead? And just to clarify, you mean 2 parts white spirit to 1 part oil?

Do you know if I can I add Molyslip Gearbox Treatment to the Didfflock?

Thanks

Edited by v8s4me on Sunday 6th March 10:44

[honestjohntoo]

adam quantrill said:

what's you're average mileage in this time? As I guess I'll have to schedule a repeat performance sometime.

Alan, probably needs to be converted to ave of 7.5 k miles per year, say 30 k miles between flushes. Ramon.

[honestjohntoo]

v8s4me said:

I don't have any ATF in the garage but I do have plenty of semi-synthetic 75W90. Can I use that to flush instead? And just to clarify, you mean 2 parts white spirit to 1 part oil?

Any relatively thin oil, simply as a carrier for the cleansing agent - white spirit.
Yes 2 part White spirit to 1 part oil.

v8s4me said:

Do you know if I can I add Molyslip Gearbox Treatment to the Didfflock?

Sorry, I don't know what a Didfflock is. !!.

[stevoj]

You don't the molyslip if your using Difflock but not sure if would it would be of any further benefit or not.

[adam quantrill]

No! Never add moly to a difflok it will never "lok" again! Also you need to make sure it's difflok hypoid as opposed to the standard oil, or else the internal brake paddles will wear out ultra fast. Reminds me - I must re-do my diff oil.