Sounds like the end of the road for my GS ownership

My pleasure Martin.

In all my years of engineering that is the strangest looking sump oil I have ever seen, especially that black residue in your rocker covers. My own GS's have ran on everything from Unipart 20W50 mineral through bulk drum Chevron and Fuchs 10W40 semi-synth to Castrol Power 1 Racing 10W50 fully-synth and have never looked anything even remotely like that.

My suspicion is your Hi-Flo oil filter had run out of filtering capacity, was in bypass and the oil had then become exhausted and overloaded with combustion deposits. A good job it had an internal bypass, ISTR a few Mk2 Golfs chewing through cranks due to cheap pattern filters with no internal bypass valves and poor servicing schedules. Luckily there were no obvious wear deposits and now with fresh oil and filter things should clean up and move any remnants into the new filter for removal. I hope your camchain tensioners get a wash out with fresh oil over time.

The next oil and filter change should finish the job of flushing plus going to 20W50 should quieten things further. As for the previous service stamps, I call bullshit, the previous owner was had by somebody (presumably cheap oil change and no filter).

I'd also say you got lucky by doing the sensible thing and not continuing to ride it if it knocked when hot. That watery oil would not have lubricated very well the hotter it got and I'd wager damage would soon follow. Oil is always cheaper than engine work.

Thinking about it, i dont recall the residue when i did the valve clearances last time - although it may have been there and i didnt twig what it was.

I only use the centre stand to park it,

Only other thing i can think of, is there is a high spot on the inner cover which is allowing oil to gather there and not run back into the sump.

then when you park and the engine is cooling, the weak thing stuff i had in there is standing and baking onto the cover.
 
You had residue in the bottom of both head covers.

Presuming your bike has remained parked on the centrestand for a while, the thin oil probably returned to the sump leaving a layer of goo (presumably carbon and products of combustion) behind.

I would expect a similar layer at the bottom of the sump which ties in with the very black oil when drained followed by the weird greyer thinner oil layer. At least the oil from your filter was just black.


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I bet that fresh red Castrol in the sump turns black very quickly. If it does, don’t panic it is just doing its job cleaning your engine and nothing to worry about.


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get 20w50 in it next change ;)

We were going to drop 4L of 20W/50 in today, but decided to do a running flush through given the state of the oil.

Hence 4L of 10W/ 40 going in (all that was available at short notice)

THe 20 /50 is ging in when i get another filter & 1K on the clock
 
Any chance of an update on how the bike is running now Mart ???


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Indeed -

I'd love to say, the pinnacle of biking luxury, purring like a swiss watch, floating on gossamer threads

Unfortunatly it's more akin to a bag of spanners chattering its way through a mangle at idle ;) in a kalashnikov way.

Engine wise it was purring until i did the change to 20/50 -

IMHO It sounds a little louder now, but that could just be me :)

The tensioner knocking noise hasn't come back, Which is good.

At idle it isnt going to win any prizes with the gearbox under no load lol

but once loaded and over 2k rpm it pulls well and will happily munch miles - It got me to Princetown & back :)

Everything else appeared to be OK until last friday when it decided to give an EWS warning on the dash.

Its gone away, but i have a new ring antenna & screws on my desk just in case.

MPG is averaging at 50mpg so quite acceptable

I'd like a newer one if i could ;)
 


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