Hi,
Which type of lubricant & method of lubrication do you recomend for the speedo drive cable?
I would guess that running some regular engine 20W50 engine down there would do the trick. If the cable has had it, just replace it.
I seem to remember reading, years ago, that you should only lubricate the speedo cable with grease, never oil. Apparently, the spinning action of the inner can ‘screw’ the oil up into the speedo head and ruin it. Seems feasible.
I have had the advice that, it would be best to use something called Waterpumpgrease…directly translated from danish. It is some white, pretty hard stuff…like old hairwax. Very sticky and water resistant.
I stand corrected. I guess if you can pull the core out of the cable assembly you could apply grease. It would be difficult to force sticky grease down the cable otherwise.
I found an aerosol can of white lithium grease that is great for this purpose.
While putting a lot of oil in a cable might pump it, that won’t damage the speedo. Depending on where the holes are, it might oil your crotch. 
I used the same white lithium after cleaning up the hardened remains of the original grease inside the speedo, so pumping it in there might be considered a good thing.
This is something of a thread revival, started by dear old John only 16 years ago!
I have a new speedo cable about to be fitted to my Sprint and I have been advised that it will likely need oiling/greasing before connecting up, though with a particular type of oil or grease.
Reading the advise above I am inclined to think that lithium grease would be good, though I wonder about silicone grease?
What is current thinking on this?
Tim
White lithium grease is perfect. Silicone greases are actually very poor lubricants for metal parts.
Tim, can you get this in the UK? https://www.amazon.com/WD-40-Specialist-White-Lithium-Grease/dp/B00L35DAWQ/ref=sr_1_1?hvadid=651211692866&hvdev=c&hvlocphy=9004494&hvnetw=g&hvqmt=e&hvrand=11357725854235447560&hvtargid=kwd-132653789540&hydadcr=977_1015116299&keywords=wd-40%2Blithium%2Bgrease&qid=1680819467&sr=8-1&th=1
Hi Tim,
This may be of interest to you (it mentions Castrol LM grease):
The images are a bit blurred, but if you open the images in another window they are better quality.
I think the cable itself may be a stumbling block though if you can’t withdraw the inner cable to apply it.
Cheers.
Al
Al, that’s a good find! Thanks for posting.
No problem Phil! They don’t make informative material like they used to!
That’s interesting, thank you Al!
Tim
You’re welcome!
“Examine every 10,000 miles…” " Do NOT use oil…"
Damn, I’ve missed at least twenty and always used oil, no wonder my speedo wavers a little.
I just replaced my MGB speedo cable with a new one from Moss, and used lithium grease (the kind you use in grease guns to lube suspension fittings). The cable is completely steady (no more bouncing), and I am happy.
I used to have erratic speedometer syndrome.
I presumed it was the rotating inner catching on the outer, so I lubricated thoroughly (I don’t recall what I used) It seemed perfect but the erratic behavior persisted.
Finally I gave up and bought a new cable and THAT fixed the problem.
Same for me. Greasing the inner on previous cars resolved the problem, but this time made only a slight improvement. Replacement was necessary.
Malcolm