TOPIC:

bountyhunter wrote: You can switch anytime, you can run syn from the start. It's a myth that engines won't break in using synthetic oil.

Is this from personal experience? My own experience from rebuilding engines is I have never managed to get the rings to seat using synthetic oils. I end up taking the top end apart re-honing the cylinders then reassemble and break in again with conventional oils. After about doing that 3 times on 3 different engines I no longer break in using synthetic oils. I have never had a problkem breaking in rings with conventional oils.
To answer the OP's original question, yes you can switch at 1200 miles. I usually wait until I have 1000 miles on a fresh engine then switch if I want to.

Just make sure you have really good gaskets!

I'm wondering if it depends on the type of synthetic oil you use for break in? Maybe the type available when it was relatively new was the extra slick type that would make our clutches slip...that seems like it would also prevent proper break in. Maybe the motorcycle specific oils with the proper friction properties would be OK for break in?

It seems the sentiment is growing that synthetic is OK for break in but there are still lots of opinions out there for both sides. I think I'm good since I have so many miles on mine anyway but I'd probably stick with conventional for break in just to be safe.

Also thinking new vehicles that use synthetic from the start are probably built with specific clearances and are somehow broken in already? It seems that certain race engines don't require break in...not sure what the difference is on those? They're built right at the track and run wide open immediately.

Well as many times as I change the oil after rebuilding a motor it would be really expensive/waste of money to use synthetic.
I change it after 30 minutes of running ,then again at 500 miles .
Then buy the time its between another 1000-1500 miles on the fresh oil its safe for synthetic in my book.
Yeah Im a little nuts about it but when I sold my 1327 last year I threw in a couple a couple of old motors 1 was an 1170 I put together 20 years ago and road the wheels off of really hard for several years before moth balling them ,the other was the old 1197 out of my z1.
Last I heard both motors looked basically brand new inside and all he did was throw head gaskets and valve springs in them since he was in there anyway and both motors are in running bikes being hammered at topeka last I heard.

Mobile 1 10W40 4T motorcycle is good because AutoZone has it in stock. The very best synthetic motorcycle oil I've found is Redline 10W40, but it is not easy to find and it costs more. The Redline oil gives the best shifting and it does not burn off when used in very hot conditions at high speeds.

wireman wrote: Well as many times as I change the oil after rebuilding a motor it would be really expensive/waste of money to use synthetic.
I change it after 30 minutes of running ,then again at 500 miles .
Then buy the time its between another 1000-1500 miles on the fresh oil its safe for synthetic in my book.
Yeah Im a little nuts about it but when I sold my 1327 last year I threw in a couple a couple of old motors 1 was an 1170 I put together 20 years ago and road the wheels off of really hard for several years before moth balling them ,the other was the old 1197 out of my z1.
Last I heard both motors looked basically brand new inside and all he did was throw head gaskets and valve springs in them since he was in there anyway and both motors are in running bikes being hammered at topeka last I heard.

Good point...I hadn't thought of that. I changed my oil at 100 miles and again around 300 miles. That would really add up $$$

Mobil 1 4T is without doubt a premier oil, some would say the absolute best. However, it is also shockingly expensive and often hard to find. Some will argue that diesel-specific oils have everything these old KZ engines need, and nothing that will do harm. Shell Rotella T is often near the top of that list and can be had for a fraction of the price of Mobil 1 4T.

These guys were making synthetic motorcycle oil long before anybody else thought it was cool

Here are a couple of interesting AMSOIL links on the subject:

Converting to AMSOIL and Breaking in a New Engine

AMSOIL Break-In Oil (SAE 30)

That's some great info from Amsoil...here's one quote from the article, "Breaking in a new engine is the one area that petroleum oil is better for than synthetics. You see, petroleum oil has a very low film strength which is ideal for breaking in a new engine. That is why we recommend you run the factory installed petroleum oil for about the about the first 500 miles. Then drain the oil, remove the factory installed oil filter and then install AMSOIL Synthetic motor oil and an AMSOIL Super Duty oil filter and your ready to go".

I'd vary the rpm's, and on the highway, accellerate and close the throttle several times a mile, first building cylinder pressure, and then with the throttle closed, pulling oil past the rings. This method will "Scuff up" the various rotating and rubbing parts for optimum break in.

The oil change after break in is very important,as the engine has shed a majority of the sharp edged pieces on the machined parts, and needs new, fresh lubrication now.

79MKII wrote: I'm wondering if it depends on the type of synthetic oil you use for break in? Maybe the type available when it was relatively new was the extra slick type that would make our clutches slip...

The myth was born because most new oils have molybdendum disulphide (moly) in them and that ruins clutches. If the oil says "energy conserving" on the label, it has moly. Slick 50 also has moly. I have never seen any convincing evidence that syn oil causes rings not to seat or gaskets to leak. As somebody pointed out, some of the very expensive new cars come from the factory with syn oil in the engines.