Synthetic Oil or not?

Synthetic does seem to exploit weakness in the sealing. Can't really blame the oil though. I use Rotella synthetic in most of my bikes.

I understand a synthetic oil has a stronger / better film, who is important when you have a engine who are not using all the time also..

I`m gone to replace head gasket + o-rings, base gasket, all o-rings for the oil pan and oil seal for oil filter and oil seal for the gear shifter and front sprocket.

I will go up to bigbore piston so the barrel and top (valves) will be overhauled.

What risk do I have for oil leaks then ? oil seal for generator and ignition pickup sensor?

I`m consider going over to synthetic..... To reduce wear and tear but I have also understood a mineral oil will loose characteristics faster when you overheat the engine? and the bigbore upgrade will give the motor some higher temp and higher risk for overheat?

Warning - Zombie thread back from the dead....
If you have oil leaks it has nothing to do with oil type.
If it's a Z900/1000/1100 engine don't use fully synthetic unless it's long chain molecule formulated for roller bearing cranks such as Rock Oil TRM 20.60 etc.

zed1015 wrote: Warning - Zombie thread back from the dead....
If you have oil leaks it has nothing to do with oil type.
If it's a Z900/1000/1100 engine don't use fully synthetic unless it's long chain molecule formulated for roller bearing cranks such as Rock Oil TRM 20.60 etc.

hehe
Should I start a new threat?

750 engine upgraded to bigbore 810cc.

Mineral ?
Semi synthetic?
full synthetic?

gordone wrote: hehe
Should I start a new threat?

750 engine upgraded to bigbore 810cc.

Mineral ?
Semi synthetic?
full synthetic?

Oil threads are like politics and religion. Nobody agrees. Thing is though, what oil to use should be scientifically based, not opinion based. Regardless though, opinions abound.

A mineral based 10W-40 is the safe choice, particularly for an engine with new rings. I doubt you will have issues with heat unless you are going to take the bike to a race track.

There is no need to use fully synth unless you like spending money for the sake of it.
The engine will be happy on mineral or semi .
Either way as long as it is for use with WET clutches you will be ok.
Normal (car) Fully synth is notorious for causing clutch slip so use bike specific if you do, but DO NOT use fully synth while running in or you risk poor ring to cylinder sealing which will result in loss of compression and oil burning.
I use Silkolene super 4 which is more than good enough.

Being devil's advocate here but there are quite a lot of cars sold these days with synthetic oil from the factory. Some people say machining tolerances are better today which may be true, but a hone is a hone and rings haven't changed all that much. That said, I run mineral oil in my 750 after rebuild but will switch over to synthetic and/or semi synthetic at some point because that's what I've got in the cabinet.

Also, the automotive grade 20w-50 M1 oil has a lot of fans in the bike community. 20W-50 oils don't have the stuff in them to wreck a wet clutch; friction modifiers that are labeled "energy conserving" are the ones to be most concerned about and those are only in the lightweight oils.

Again, I'm playing devil's advocate here, not strictly recommending. Just making a point that there are counters to many of the arguments that people make regarding oils.

hehe thank you for your replay

So I don`t need to focus on the film is better on synthetic, it`s good enough on mineral also?
I was thinking about cold start in Norway, typical 53.6 - 59 degrees Fahrenheit

But when I have rebuild the engine with new pistons and top was the plan to use mineral oil and new filter for burning in period,
running for around 500 miles and then dump the oil and on new with new filter?

gordone wrote:
hehe
Should I start a new threat?

750 engine upgraded to bigbore 810cc.

Mineral ?
Semi synthetic?
full synthetic?

I run Rotela 15w40 mineral oil in the motor in my sig. and will never use any other oil it works for me YMMV.

I used reg 10/40 Valvoline and changed it and the filter out at 100..... 300 and then Valvoline 10/40 bike oil at 600 miles....... the 300 miles change might have been over kill but I had a fair amount of assembly lube, wd40 and STP mixed in and wanted to get it all out along with the glitter of the cyl walls breaking in.

I believe it was Wired George as winter took hold that coined the phrase: "an oil thread is a clear sign of CRS. Can't Ride Syndrome".
I've read a bunch of oil threads but most circle back to issues with synthetic in a wet clutch environment. Flat tappets like zinc and phosphorus as well.

I spent 20years working in Navel Aviation...all the jet/turbo fan motors I'm aware of used synthetic oil. Dino simply would not stand up to the heat these motors generate. I wasn't around aircraft piston motors so I can't speak for them.

When I switched from Dino to synthetic in my C14, I noticed a much smoother shift when shifting gears p or down.
I have not made the change from Dino to synthetic in my Z1 900 yet and find it interesting the comment of using a semi synthetic for the bearing interesting. I might try a part synthetic just to see what happens. Maybe the shifts on the 900 will smooth out too.

And yes I suffer from CRS....to flipping cold and too much snow on the roads at this time.
.