Forum

[martyn]

I am about to change the oil spec. on my G5 (EFI). I am changing from fully synthetic to part synthetic, (on the advice of my well qualified mechanic and biker friend)
The manual does say semi synthetic, but for some reason, I have been oil changing with fully synth. My mechanic, says absolutly no need for full synth., plus is more expensive,etc etc.

Therfore he recomends an oil flush to, ammongst other things, de-glaze the bore.

Any body have any interesting thoughts on the matter?

[PeteF]

Well he's right that you don't need full synthetic but I can't see how an oil flush will de-glaze the bore. What does he suggest you flush with?

[trevorch]

All mechanics have opinions, but not all the same and we riders also have preferences that are different.
My B5 came with standard, as new, semi. (I live in Switzerland where winters are somewhat cooler than most of UK)
I decided to change to a 15/40, but my dealer insisted I go back to a 20/50 Semi. I found no difference and I have now had about 8 months of each. My dealer in fact suggested an even lighter winter multi (5W/50) but this does not exist. His argument in favour was the the hydraulic tappets would be quieter. (They are almost as noisy as my old 2007 Bullet.) No difference in oil consumption - I had never had to top up between oil hanged, so far. Can't hear tappets any more, since I changed to our hosts sportier silencer.

Cheers TrevorCH

[Martin (Sale Mcr)]

To Flush or not to Flush, that is the question. as they say.
But how do you flush out the flushing oil, as there is a lot of oil left in the engine after the drain plugs have been removed, and all the drips have stopped.
The timing case and the gunge at the bottom of the oil tank etc.

If I was thinking there was a need to flush, I would flush, and drain then refill with a cheap 20/50 oil and run / use the bike, to get the engine and the oil tank as hot as possible, then drain while still hot.
The main aim being to get out as much of the flushing oil as possible, this being more important than the move to an other oil type.

May I ask when was the last time the the crankcase was split, as this is the only way to clean out the gunge that forms at the bottom of the oil tank.

If you are going to all that trouble to clean out the old before putting in the new.

The reason I ask about the splitting of the crankcase is that I have recently split mine, and was very surprised at what I found. The oil had been drained the day before.
The engine was in a tray on the bench, the case was then split by say half an inch apart and left for the night.
The next morning the case was fully split, and the crank removed. Only to find about a half inch of gunge in the oil tank halfs that did not want to flow. It wiped out cleanly with a cloth.
I am sure that some are saying he does not change the oil often enough.....The oil has been changed every 1000 /1200 miles or every year, which ever comes first, including the oil filter, using a good quality branded oil. The bike is a 350/89.

Would I use a flushing oil NO, why because the oil sits in the oil tank, with no agitation, only moves around the engine very slowly. Would I use a flushing oil in an old car Yes.

I am sure others will say things are different with the EFI, than in the iron classic

Just My 2p worth of old sump oil.
Martin

[grunda 12]

hi martin ,i wouldn,t bother flushing the engine ,just change the oil & filter also clean /check wire strainer on underside of engine secured with plate and 2 m5 bolts ,don,t forget to put 25ml of oil in primary case,i find leaning bike over on centre stand gets 99% of the oil out also drop it while its hot (the oil)atb paul.

[Martin (Sale Mcr)]

Paul,
My point was that I was more bothered about getting rid of the flushing oil, "If I was going to Flush, which I would not do in the first place, particularly as I was surprised by the amount of oil that was left in the oil tank, after drain, then spiting the cases.
I agree with you about changing the oil and filter.

Martin

[PeteF]

There are also flushing additives which you add to the old oil and run for a bit before draining. I assume they increase the detergent properties of the oil to flush out the gunge.

[jaffa90]

Not to flush,why bother semi/synthetic oil is mineral/synthetic oil.

[neddy]

I will go with the no flush boys also

[martyn]

Sorry about the delay in getting back to you.
He, (my mechanic friend),suggests an oil flush (engine flush) of the additive type (say Motul).
You apparently add to the existing oil, run to get hot, and drain. Supposed to also remove all gunge from oilways, "cracks & crevices". Also de-glazes the cylinder bore's.( he claims car engines from new, running on fully synthetic, eventually have cylinders that become glazed, thus resulting in a certain loss of compression)

I am also aware that a certain ammount of oil remains in the engine after draining, but as grunda 12(Paul) says, most can be removed by tilting the bike over. (to those not too knowlegable with the EFI, -there is no oil tank, apart from the crank case) The filter and strainers are always changed and cleaned at every oil change.
So with Paul's theory, if only 1% of oil remains in the engine, that would mean a further dilution of the remaining diluted engine flush!!
Thanks for all of your responses, guys. Always interesting to know that you can get a lot of interesting viewpoints