I've been looking for a straight 30 oil suitable for fluid flywheel and gearbox and came across this oil. I was a bit surprised to read in their technical information: 'Oil change every 600 miles'. Can this be correct?

I would add a "0" and divide by 2 although the fluid flywheel oil doesn't need changing of course.

Ranald,

Use the cheapest 30 grade you can buy for the flywheel. It does not deteriorate.

Comma should be OK for the gearbox. As Andy says, change gearbox oil every 3000 miles or once a year. Drain when hot, tip in a couple of pints of paraffin, run at tickover in neutral for 5 minutes, drain paraffin and refill with new oil.

Neil

Paraffin? Really?

could be some ancient mechanic's trick to "clean" a gearbox, like running an engine with diesel oil as a cleaning agent. Do,t ask me if they work or not.

Yes, according to to Drivers Instuction Manual, draining and flushing with Parrafin is correct, also same procedure for Rear Axles. Except you just need to rotate the Axle by hand a few times before allowing to completely drain.

Cheers A'l

How would the oil get dirty? or was this needed with the oils of those days? or was it to flush out metal particles?

Goodness me well if that's what the manual says.... but
I wouldn't like to use paraffin, there will be a residual amount left in the box which would act to break down the new lubricant.
I'd rather change it again at 500 miles if there is a need for flushing through. The gearbox oil doesn't reach engine oil temperatures and won't deteriorate anything like as fast as the engine oil so maybe 3,000 miles was some sort of insurance against failure.
However this post has prompted me to have a look at mine as I can't say it's ever been changed! (same with the fluid flywheel )

Well, Graham, if you want to ignore the manual, that's your privilege - it's your car when all is said and done.

The reason they tell you to flush out with paraffin is to scour the box of any brake band dust. Whilst this will be put in to suspension in the oil, it will still stick to the internal parts. The miniscule amount left will not have a lot of effect on the new oil and will evaporate, even with the low gearbox temperature, after a few miles anyway.

I can assure you that I have been using this method for 25 years and have never had any gearbox trouble directly or indirectly pointing to the paraffin doing any "damage". I do recall one car, the gearbox oil was WHITE with all the band dust. It actually took TWO flushes with paraffin to get it clear. Had I not flushed, all the residual dust would have nicely surged around the box and maybe would have affected the gear trains.

There is no need to ever change the oil in the flywheel as it does not deteriorate. (Unless of course you are overhauling the unit - even so, you can refill with the oil you drained off!!!)

I see now, I understand that. Now I'm really worried about the state of mine! Morris Oils order going in now.