Having just rebuilt my engine again...... what is the view on oil and oil filters ? Mineral, semi synthetic, or fully synthetic.Has anyone had experience with oil filters on the return line ? I have looked at the DC motorcycle element type and the trials bits screw on type.

any suggestions/recommendations

I'm interested in this discussion too. I've just rebuilt the clutch on my 350 unit twin and wondered if anyone has any specific recommendations for clutch oil?

I have a 5lt container of Putoline 10/40 sport semi synthetic, unused (had it for a road bike i have since sold) would this be suitable for the engine in my cub? as with other view's i was going with ATF in the primary, 100ml? not sure there. Gearbox, i have been told to use a light gear oil, but in my Fantic 200 i have always used straight 30wt oil (millers) good spec rating and cheap too no clutch slip either, would this be ok in the cub gearbox. How much oil in the g/box?

I have a 5lt container of Putoline 10/40 sport semi synthetic, unused (had it for a road bike i have since sold) would this be suitable for the engine in my cub? as with other view's i was going with ATF in the primary, 100ml? not sure there. Gearbox, i have been told to use a light gear oil, but in my Fantic 200 i have always used straight 30wt oil (millers) good spec rating and cheap too no clutch slip either, would this be ok in the cub gearbox. How much oil in the g/box?

Blimey does nobody workaround here ;-) ???

I am not sure about the ATF for the clutch, the oil is there to lube the chain and the clutch bearing (which only moves when the clutch is pulled), I prefere a lubricating oil and use 150 ml SAE 30 with out problems.

There is hollow tube through the middle of the gearbox drain plug which is sealed with a screw in the middle of the plug. Remove the screw and fill until oil comes down the tube.

Again I use SAE30

I always use ATF in my clutches and gearboxes - working on the theory that it's inexpensive, and light enough to help reduce drag. It also has a good cooling effect and helps reduce clutch slip. Plus I figure if the bearings, gears and clutches in my old Yank V8's auto boxes would stand 500bhp through them, I wouldn't break anything with the power of a 250cc Sunbeam scooter engine.... :-)

I asked Martin Adams of Serco before he went down under what oil he would recommend for the rebuilt Cub.

He said in his normal blunt manner "If you've spent that much on the engine you should use the best oil in it".

Fully synthetic was his advice for the engine, changed on a faily regular basis. I've since used the heavier grades and have not even had to put new rings in for the last two years.

The problem is that synthetics desolve the deposits and carry them back to the oil tank. Without a modern fine filter these particles continue to go round and round. So I change the oil every couple of months. Dave Varley's 'Unique' & compact oil filter( http://www.dcclassicmotorcycles.co.uk/part..._filtration.htm ) looks the business where space is limited and should help catch the bits.

In the clutch a small quantity of ATF, enough to keep it wet, has served well and avoided the common Cub clutch slip problem.

In the gearbox I use 20-50 non synthetic and have had no problems.

Lots of theories around - but these make sense to me.

Keep on Cubbin'.