Synthetic oil and carbon build-up

I'm considering using Mobil 1 V-Twin synthetic in my Commando. I've put about 1200 miles on it since I put in new pistons/rings.
Since the oil is synthetic and not made from a carbon based feed stock I'm thinking it should reduce carbon build-up on the pistons and head.
Although gasoline may leave carbon at least any burning of the oil won't. The flash point of the synthetic at 500 F also makes this less likely.
The Mobil 1 has the zinc needed for the lifters and receives a good write up by this author in this oil article. http://www.realclassic.co.uk/techfiles/oil030319.html

Has anyone been using a full synthetic for quite a while, then had the head off and seen if carbon deposits were minmal?

TIA
Bob

Have used Amsoil 20/50 for 4 years until economy (and no work) made me go back to straight 40 last year. Had to strip the engine for a cam and lifter change beginning of 2010 and yes it seemed cleaner. I did break in the last set of rings the hard way with minimal assembly oil in the bores and a harsh but quick breakin. Less rubbish on the mag sump plug as well.

rx7171 said:

Since the oil is synthetic and not made from a carbon based feed stock I'm thinking it should reduce carbon build-up on the pistons and head.

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Just out of curiousity, what do folks imagine common run-of-the-mill synthetic oil is made of ?

FYI, synthetic oils are mostly synthesized from a starting point of natural gas.
Guess what that is ? Yup, carbon and hydrogen.

And if your engine is tight and doesn't burn much oil, shouldn't make any difference anyway...

??

P.S. Its largely the amount of detergent in the oils additive package that can dictate how clean it will actually burn.

Aircraft oils have long had to have a low metallic content, or hard carbon deposits buildup in the combustion chamber can cause problems. This technology is slowly filtering into auto oil technologies - partly because of the requirements of catalytic convertors, which in general don't like metals in the combustion residue...

hth.

Perhaps also not appreciated is the amount of chemistry that goes into fuels. They also have a complex blend of things that ensure clean combustion - you rarely see this discussed or spelled out. For most fuel companies, its probably on the secret list too.

Tetrylethyl lead (in the fuel) required a complex series of halide scavengers in the fuel, to keep those rock hard deposits from forming in the combustion chamber.

You wouldn't want to eat any of those....

So the brand of fuel you buy could have as much bearing on carbon in the combustion chamber as the oil you use. Perhaps more bearing...

Rohan - always interesting.

I've heard that our fuels in the US actually burn slower than those of the past, that this is what enables/demands the high compression ratios of so many late model engines, and that the slow burn of current fuel causes higher exhaust port temperatures and fuel continuing to burn in the header in many engines of older/lower compression design.

Your thoughts?

Whatever the flashpoint of the oil, its not going to make any difference in the combustion chamber either - the temps are going to be well above 1000 degrees in any medium to hard running, and probably lots more, no oil will survive that unscorched...

Opethiselps.

xbacksideslider said:

I've heard that our fuels in the US actually burn slower than those of the past,

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Don't know - never seen this quantified.
High octane rating is sometimes linked to slow burning fuels, as in avgas for piston engines.
But some of these current engines in high performance cars and bikes sure don't need slow burning fuels.
So is it slow burning, or very resistant to exploding - and is there a difference ?

Cheers.