Synthetic or Semi Synthetic Oil

[Rob 131 Sport]

I have a 2015 Kawasaki ZX6R 636 Performance Edition. It’s due an oil change and previously I’ve always used a Part Synthetic 10W-40 Oil.

I was thinking of using a Fully Synthetic and then had a niggle in my mind that the Clutch / Gearbox necessitated a Semi Synthetic. Searchers I’ve done on the internet have been somewhat inconclusive.

Advice regarding this would be much appreciated.

[Krikkit]

I managed to find a copy of the user manual for the non-perf edition and it says full or part synthetic 10w40.

Personally I'd use fully synth

[ChocolateFrog]

Always fully synthetic.

Semi-synthetic is a largely meaningless marketing term.

[scorcher]

Fully synth should perform better but you won’t notice it. Regular changes more beneficial. I doubt there’s really a bad oil out there.Stick in whatever Kawasaki recommends and ride it.

[SAS Tom]

Fully synth is better. Think of semi as the minimum option. Fully synthetic will outperform semi synthetic.

[LordFlathead]

I always follow the OEM guidelines (unless you're racing). They spent millions designing your engine and know which oil offers the best performance.

DON'T do what I once did.. filled my CBR1000F with Slick50.. then had to have a new clutch fitted due to slippage /utter tt

[fred bloggs]

SAS Tom said:

Fully synthetic will outperform semi synthetic.

Do please elaborate. Is engine power increased, or economy, Or engine life ?

My suspicion is It makes F all difference. Any difference in performance or economy is so minute as to be undetectable, and In my 25+ years as a bike mechanic, I've yet to see an engine fail because it had semi synth instead of fully.
99.9% of bikes die from crashing or corrosion,(or NO oil)

As long as its the correct viscosity, and its for a motorcycle with a wet clutch, its fine.

[Rubin215]

I was explained to me that fully synth is better for the unsympathetic owner; the guy who revs the tits off it everywhere, does a handful of trackdays every year and only changes the oil once in a blue moon.

Fully synth takes longer to break down in extreme use and is slower to degrade overall.
For the vast majority of owners doing normal miles, normal use and reasonably regular servicing a semi-synth oil is more than adequate.

[KTMsm]

I always go for a cheap but MA2 spec, fully synth and then I change it regularly - I buy it in 20L off ebay

Semi synth is pretty meaningless

[Rob 131 Sport]

fred bloggs said:

SAS Tom said:

Fully synthetic will outperform semi synthetic.

Do please elaborate. Is engine power increased, or economy, Or engine life ?

My suspicion is It makes F all difference. Any difference in performance or economy is so minute as to be undetectable, and In my 25+ years as a bike mechanic, I've yet to see an engine fail because it had semi synth instead of fully.
99.9% of bikes die from crashing or corrosion,(or NO oil)

As long as its the correct viscosity, and its for a motorcycle with a wet clutch, its fine.

Yes it was the wet clutch issue I was concerned about with fully synthetic. I’m assuming this isn’t a problem.

[KTMsm]

Rob 131 Sport said:

Yes it was the wet clutch issue I was concerned about with fully synthetic. I’m assuming this isn’t a problem.

It isn't a problem if your clutch is ok - it may well show up a worn clutch - for want of a better term fully synthetic is more slippery

I had this issue - changed to fully synth, clutch immediately slipped - I measured and it was out of spec, replaced 3 plates and all was fine.

[Krikkit]

KTMsm said:

It isn't a problem if your clutch is ok - it may well show up a worn clutch - for want of a better term fully synthetic is more slippery

I had this issue - changed to fully synth, clutch immediately slipped - I measured and it was out of spec, replaced 3 plates and all was fine.

Would've been interesting if you'd swapped back to fresh semi synth to see if it was just suspended friction material that was just keeping the clutch going...

[KTMsm]

Krikkit said:

Would've been interesting if you'd swapped back to fresh semi synth to see if it was just suspended friction material that was just keeping the clutch going...

I did - it still slipped

Swapped 3 (out of IIRC 7) plates which put it back into spec and it works fine
(still have the bike, over a year on)

It would have been a better test if it was the same manufacturers semi V full but it wasn't as I switched to bulk buying

[Birky_41]

I run a high quality semi synthetic on my gsxr track bike, my Mx bikes and anything I change the oil often. No clutch slip, oil doesn't break down and never had a mechanical failure in road riding, or mx racing for last 2 decades

I run fully synthetic in my Aprilia 1100 because the oil is in that 9-12 months of the year, toured tracked and hammered. That is the only bike I run fully which is motul 300v

The others are all motul 5100

[Bob_Defly]

fred bloggs said:

SAS Tom said:

Fully synthetic will outperform semi synthetic.

Do please elaborate. Is engine power increased, or economy, Or engine life ?

My suspicion is It makes F all difference. Any difference in performance or economy is so minute as to be undetectable, and In my 25+ years as a bike mechanic, I've yet to see an engine fail because it had semi synth instead of fully.
99.9% of bikes die from crashing or corrosion,(or NO oil)

As long as its the correct viscosity, and its for a motorcycle with a wet clutch, its fine.

Hardly any bike will fail these days if it's had regular oil changes, as they are generally all built pretty well. But full synthetic performs much better than anything else, and will hold it's properties longer too, under harsh conditions. I have worked in the oil industry for a few years, and we had a test lab on site.

[SAS Tom]

Bob_Defly said:

fred bloggs said:

SAS Tom said:

Fully synthetic will outperform semi synthetic.

Do please elaborate. Is engine power increased, or economy, Or engine life ?

My suspicion is It makes F all difference. Any difference in performance or economy is so minute as to be undetectable, and In my 25+ years as a bike mechanic, I've yet to see an engine fail because it had semi synth instead of fully.
99.9% of bikes die from crashing or corrosion,(or NO oil)

As long as its the correct viscosity, and its for a motorcycle with a wet clutch, its fine.

Hardly any bike will fail these days if it's had regular oil changes, as they are generally all built pretty well. But full synthetic performs much better than anything else, and will hold it's properties longer too, under harsh conditions. I have worked in the oil industry for a few years, and we had a test lab on site.

Pretty much this. It will lubricate better under worse conditions for longer. Will you be able to tell the difference between having a blown up engine or not, probably not but there’s no denying that full synthetic is the better oil. No oil company will tell you different. Some may claim a power increase in some applications.

[Krikkit]

KTMsm said:

Krikkit said:

Would've been interesting if you'd swapped back to fresh semi synth to see if it was just suspended friction material that was just keeping the clutch going...

I did - it still slipped

Swapped 3 (out of IIRC 7) plates which put it back into spec and it works fine
(still have the bike, over a year on)

It would have been a better test if it was the same manufacturers semi V full but it wasn't as I switched to bulk buying

So it wasn't fully synth then, just dropping the oil with suspended clutch material and replacing without.

Common problem with automatic gearbox oil changes.

[DJP]

The main benefit of fully synth for a road vehicle is longevity – synthetics last longer and keep the engine cleaner, because they contain fewer impurities, than mineral or semi-synth oils.

They aren’t more “Slippery” and they don’t cause clutch slip as such.

However, they can have greater detergency than other oils. So if your knackered old clutch is held together with baked on mineral oil deposits, you may find that changing to a synthetic cleans it up and it starts to slip. That’s not the oil as such, it’s just a dying clutch.

I’ve run my last 6 bikes on fully synth from new with no issues and these days the price difference is so small that I see little point bothering with cheaper oils.

[Yazza54]

My race car runs a sc59 cbr1000rr engine, I always use fully synthetic motul 7100 and the clutch never gives me any problems, and it gets a lot more abuse than it'll ever get in a bike.

[KTMsm]

Krikkit said:

So it wasn't fully synth then, just dropping the oil with suspended clutch material and replacing without.

Common problem with automatic gearbox oil changes.

It was - the bike's oil was changed every 18hrs or so but I'd tried to get back to the van with a clutch slipping so badly it couldn't even move itself in the end