Hitchcocks Forum

Hi Chaps,
I'm doing an oil change on the 2008 500 Classic right now.OK I've taken a break to send this in!! Question,is it ok to flush out the oil tank with paraffin? I've noticed some sludge dripping from the drain hole and I'd like to clean it out.I have checked the various filters and they are clean and sludge free so I don't think there are any problems.In my Triumph days I would remove the oil tank every year or so and flush it out but that was completely separate from the engine.Any comments would be welcome.
Cheers DaveP.

Dave, I would leave well alone. The little bit of sludge that's there is likely doing no harm. It's going to be a lot harder to remone any residual paraffin from the engine than it is from a Triumph oil tank of old.

Edward makes a good point..My first reaction was no but then i think, why not? The only proviso would be to ensure the oil way to the pump flow pick up chamber doesn't become blocked.
If the middle drain plug which has a screen filter attached is removed, then you should get paraffin draining through from the tank.

A good flow proves passage is clear to the pump flow pickup.... A torch shone in through the filler hole and a metal scraper fashioned from an old spoke with a flattened angle on the end would do as a shifter.... Obviously wash as much sludge as you can through the tank drain..... gwilly

Did you drain it hot? If so I wouldn't bother.
If not, I still wouldn't bother, do it hot next time as soon as you can after stopping the engine.

How about putting some cheap "thin" oil in, run until engine is warm/hot, drain and do the oil change as normal if you are worried about the sludge.

I wouldn't do it. Doesn' t take long for oil to drain out of the tank through wet sumping, so paraffin I would imagine would be quicker. There is too much risk of getting some trapped in there. Regular and frequent oil changes are the key. I change mine about every 1300 miles, maybe a bit wasteful, but no sludge.

Thanks for the replies chaps.Yes I did drain it hot,always do.The Reason for my concern is that I don't know how high above the bottom of the tank the draw off point to the pump is situated.In the event I did flush the tank with paraffin and moved some crud.How much is left in there, I don't know.However,I refilled the tank with Halfords 20/50 and started her up.Very smokey for a few minutes as the residual paraffin found its way past the rings and burned.Then all clear and a forty mile ride along the Warwick Northants border in the sun and no apparent harm done.
Next time I'll get some proper flushing oil! I know that some of you guys have had these motors stripped down.Can someone tell me please how high the delivery pump draw off drilling is above the tank "floor".Cheers Dave P.

Let me reiterate and emphasise the importance of leaving off the middle drain plug..

Wet sumping or ingress of paraffin into any part of the engine cannot occur unless that middle plug is left in..

Whereby fluid finding its own level would indeed prime the pump and maybe find is way to the big end and sump...

The problem here is the op needs to remove sludge from an oil tank.. Now barring a crankcase split, i think with care it is possible to flush through a tank without detrimental effects.
Of course the knack is to oil change regularly and not allow sludge to build up.. But if for example you have just acquired the machine and found this problem developed by a previous owner, then what else could be done? Interesting i think.. cheers gwilly.

The base of the oil "tank" is pretty flat and the drain plug is as low as it can be. It should drain pretty well. Rocking the bike side to side might get a bit more out. Depends how sludgy the sludge is.

Dave I just happen to have some split 500 crankcases in front of me. The draw off hole is quite hard to see as its around a corner. Feeling with my finger I'd say there's about 5mm from the hole to the bottom of the oiltank so any significant sludge is likely to get sucked up. This is a 58 Redditch one so there may be some differences from the Indian version.