synthetic oil causes leaks..true or false..
The answer is both..
In the old days we only had oil..it came out of the ground and we used it..
Then we started grading it, a bit like we do with milk really..
Then we put additives in it and then we made it from vegetable matter..
But in the beginning we had oil..now the oil lubricated the inside of our engines and as it got hot it ran through the bits it should and when it got too hot it burned and stuck to the inside of the engine in the same way cooking fat will run when it is hot and stick when it burns..
We would replace the oil with new oil and the old burnt oil would stick to the casing, this would stick in any crevasses in the gaskets as well which helped to seal any imperfections,
Then someone invented synthetic oil and because it was synthetic or man made, they found they could make it lubricate and also clean the inside of your engine at the same time, and that is exactly what it does..so if you have an old bike that has been running for years on mineral or dino oil and the oil has filled any cavities the synthetic oil will wash it away and leak out through the newly cleaned gaps..
Now is the synthetic oil causing leaks or simply cleaning old burnt oil that was plugging them.
If you have a new bike synthetic oil will not cause leaks..
Now clutches are a different matter..if you want a clutch plate to grip would you coat it in the same stuff they use to make a frying pan non-stick..
John.
Nicely put but I'm not sure I completely agree with everything you say. True modern engines are designed to run either dino or synthetic oils without leaking. They used to say older engines would not run as well. For instance for years guys talked about how old Ford flatheads needed to run on non-detergnrt oils because due to the lack of true valve seals a certain amount of "sludge" was necessary for the engine to run right. They also claimed that the types of gasket material used on old engines, synthetic oil would leak because synthetics do not swell up gasket material the same way dino oil does. And lastly even though synthetics protect your engine better than dino it is typically a thinner weight and as such will seep out faster than thicker weight dino oils. The fact is none of this is true. Yes, if the engine leaks, it will leak more with synthetic because it is thinner but if it doesn't leak synthetic should not make any difference nor should it turn a tight engine into a leaker.
Older engines leaked... period. Oils with detergents, dino or synthetic did as John indicates on older engines - and old synthetics likely did create a few problems. We used to have a laundry list of things you had to do to "break-in" and engine. Some were necessary, some simply myths. Most modern engines really don't need a break-in anymore... rings seal perfectly fine without it nowadays. Those days are gone.
Viscosity is the same for synthetics as dino... so no worries there.
Synthetics stand up to heat and moisture far better than dino. And, as long as there are no anti-friction modifiers, synthetics run great in our wet clutches. I have used synthetics in all my vehicles for --- ah... a VERY long time. While its purely anecdotal, I have never had an oil related failure/problem in any of my vehicles while using synthetics. Wish they'd had it when I was driving my 73 Jag XKE 12 cylinder... I will wager that engine would still be ticking.