Why double the oil for break in but not synthetic?

[fsds123]

Why during break in of a rebuilt motor can you not use synthetic oil in fear of too much lubrication not seating the rings properly...but it is recommended to use double the regular oil for extra lubrication. Or am I missing something?

 

[ezeke]

Re: Why double the oil for break in but not synthetic?

Where did that advice come from?

 

[tashasdaddy]

Re: Why double the oil for break in but not synthetic?

have not heard the bit about synthetic. where did you hear it.

 

[fsds123]

Re: Why double the oil for break in but not synthetic?

Nobody in specific, but on this site and on others doing a search for "break in" and "synthetic" gives you posts where people say not to use synthetic during break in, with some even stating their dealer or mechanic told them so.

I take it that is not the case and I can go to full synthetic now?

 

[ezeke]

Re: Why double the oil for break in but not synthetic?

It is not logical; you double the oil to maximize lubrication and synthetic oils are the maximum lubricants of TC-W3 oils.

Here is a link to an old thread that helps to explain the differences in lubricating oils and the results of testing: http://www.carcraft.com/techarticles/synthetic_vs_conventional_oil/index.html

 

[jakebrake]

Re: Why double the oil for break in but not synthetic?

i agree with everyone else....you are being told to double the volume (not viscosity) of oil in your crankcase? you will blow every seal in the engine if that engine has any oil pressure whatsoever. You will barf oil out of the dipstick, and propably flood the cylinders so bad, the boat will smoke like a cropduster.
as far as synthetic, in the old days of synthetics, it was notorious for finding any and every spot in a gasket or seel that it could squeeze through.

break in with fossil, swith to synthetic afterwards if you feel so inclined, and change at the proper intervals. i don't care what the oil company says.

 

[tashasdaddy]

Re: Why double the oil for break in but not synthetic?

jakebrake, you are speaking of a 4 stroke motor. these are 2 stroke with no crankcase bath. lubrication is deliver by mixing with the fuel. the recommendation on break in, is to double the amount of oil, mixed in the fuel. the motor normally runs on 50:1 ratio, break in is a 25:1 ratio.

yes with the double oil, the exhaust will be more smokey.

 

[ezeke]

Re: Why double the oil for break in but not synthetic?

What seals jakebrake? His motor is a 1979 115 crossflow two stroke.

 

[fsds123]

Re: Why double the oil for break in but not synthetic?

break in with fossil, swith to synthetic afterwards if you feel so inclined

This is what I was referring to...many people say this, but I guess it is one of those often repeated myths.

 

[JB]

Re: Why double the oil for break in but not synthetic?

You have 2 strokes and 4 strokes mixed, fsds.

It is 2 strokes that want double oil during break in.

It is often recommended not to use synthetics in 4 strokes during break in because they are too slick to allow the rings to seat well or quickly.

 

[fsds123]

Re: Why double the oil for break in but not synthetic?

You have 2 strokes and 4 strokes mixed, fsds.

It is 2 strokes that want double oil during break in.

It is often recommended not to use synthetics in 4 strokes during break in because they are too slick to allow the rings to seat well or quickly.

I'm well aware that only 2 strokes require double the oil...can't really do that with a 4 stroke. I am referring to the point some people make that synthetics are too slick to allow proper seating of the rings in 2 strokes, yet then say to use double the oil for the extra lubrication.

On a side note...if synthetics are too slick for break in for a 4 stroke, why double up on the oil in a 2 stroke? Whats the difference? Both have pistons and rings that require seating.

 

[mhg]

Re: Why double the oil for break in but not synthetic?

It has to do with the way the cylinder walls are lubricated in the 4 stroke
In the 4S the cyl. are sprayed with oil under pressure from below the piston
This way there is a serious amount of lube between the rings and the cyl.
If you used a super slick synthetic the rings will not seat properly

In the 2 stroke there is much less oil in the lubicating cycle due to the nature of the lube system, and the cylinder is lubed both top and bottom of the piston at the same time
this means one less part in the 2S as there is no need for the oil control ring

during break in you have more friction due to new parts not fully mated to each other and so a little more oil is a good thing

the added oil does raise the viscosity of the lubricating fluid (25/1 gas and oil) as you have 2X the oil in the same amount of gas

 

[steelespike]

Re: Why double the oil for break in but not synthetic?

Its not only lubication but the extra oil serves as a flushing agent to carry away any contaminates.