Sylar wrote:Data, i always use part Synthetic, going on the theory that up to about 20,000mls the engine is not truly run in. I would then think fully synthetic would be okay, is my thinking at fault?, I normally do 10,000mls per year.

Hi Sylar, no...your thinking is ok. There is not really any right or wrong to this. Except don't put fully syn in a bike that has not yet finished conforming ie: not done enough miles to allow the engine to fully run in. Which is what you are saying. It reduces the engines ability to conform so let that process finish first. You could use fully syn much earlier in your bikes though. The general rule of thumb, arrived at by the oil scientists is that air cooled engines normally finish conforming enough to use fully syn at 5,000 miles, and liquid cooled engines at 6,000 miles. The reason for the difference is the tighter tolerances on the liquid cooled engines and the better cooling preventing the running in process happening quite so quickly.
The main thing is...fully syn reduces engine wear to almost zero in any engine. Is that good or what? Doesn't matter what engine it is. It works. It can make the difference between getting to 100.000 miles or more trouble free and with no valve clearance adjustment, or maybe having to give the bike more maintenance on a semi or mineral. The small extra cost can in fact be recouped too as you get a bit more mpg and/or power. All proven. If you buy your fully syn from Johnson and Allen (biggest oil supplier in the UK) over the net with free delivery, it can cost less than semi.
And then there are the engines in bikes like Truimphs which have a mineral or semi syn oil in until the first service and then go to fully syn straight away before conforming has fully taken place. And cars of course which almost exclusively run fully syn from the word go. What about them? It's to do with the engineering, the way the engines are built and run that makes the difference. But won't go there. My disease will makes itself too prevalent! (Bluebottle knows what i'm talking about) It's already showing here....
