Question on Break-in Oil...

...I am getting ready for my first engine start (new Superior O-360) using the recommended break-in oil. I have Van's Oil Pressure line and restrictor fitting installed going to the oil pressure sensor.

The question I have really comes into play AFTER the engine break-in period. Do I need to drain the mineral oil (break in oil) out of the oil pressure sense line as I switch over to the "normal" recommended oil after the engine break in period? Or does it make any difference in the grand scheme of things??

noelf said:

...I am getting ready for my first engine start (new Superior O-360) using the recommended break-in oil. I have Van's Oil Pressure line and restrictor fitting installed going to the oil pressure sensor.

The question I have really comes into play AFTER the engine break-in period. Do I need to drain the mineral oil (break in oil) out of the oil pressure sense line as I switch over to the "normal" recommended oil after the engine break in period? Or does it make any difference in the grand scheme of things??

Click to expand...

I am at the same plot with engine break in and do not plan on draining the sensor line. I don't think it matters.

What is important is to not go back to mineral oil after the change or to run with mineral oil beyond the time needed to stabilize oil consumption. Some engines break in sooner than others. The whole process is to get the rings seated and then make the switch to the ashless stuff. A friend experienced NO oil consumption whatever during the break in with a Mattituck engine, it is running fine after a couple hundred hours.

My engine ran about an hour and a half on the Barrett dyno and I have feeling it is nearly broke in already.

It really doesn't matter. You are going to have oil hanging around in other cavities. It will be compatible with whatever you decide to run after the break-in period.
As far as the oil pressure sense line, I bet that bubble of air will pretty much purge it any way.

Randy Hooper

What is important is to not go back to mineral oil after the change or to run with mineral oil beyond the time needed to stabilize oil consumption. Some engines break in sooner than others. The whole process is to get the rings seated and then make the switch to the ashless stuff. A friend experienced NO oil consumption whatever during the break in with a Mattituck engine, it is running fine after a couple hundred hours.

Click to expand...

David,

This has been my experience as well. I've been breaking in a Superior XP-IO-360, and have had no oil consumption. I have the sump full to 7 qts, figuring anything over that just gets blown out the breather line. So far so good.

Mark

Its clearly not a problem because the oils are compatible, but perhaps someone who knows oil can answer this?

With most brands is the content of the breakin oil in fact a subset of the AD oil? I presume that to be the case but have never been quite sure.

Aeroshell Answer Book

http://www.shell.com/home/content2/aviation-en/aeroshell_site/theanswerbook.html#10

"Can I switch from a straight AeroShell mineral oil to a single grade ashless dispersant oil, or even a semi-synthetic multigrade oil?

All AeroShell oils are compatible and can be mixed with each other. Many single grade customers try AeroShell Oil W 15W-50 during the colder part of the year, then convert to using it year round. Others, however, choose to alternate between single grade and multigrade depending on the time of year. Either system works well because AeroShell oils are entirely compatible and can be interchanged as desired. In addition, if you need to replace a cylinder on a mid-time engine, you can switch from AeroShell Oil W single grade or AeroShell Oil W 15W-50 to a straight AeroShell mineral oil for one or two changes to break in the new cylinder. Then you can switch back to the ashless dispersant oil after the rings are properly seated. If you have a mid-time engine that has been run exclusively on a straight mineral oil and wish to try an ashless dispersant oil, use caution. The introduction of an ashless dispersant oil into your engine could loosen up some of the carbon deposits. So check your oil screens and filters often to ensure against oil starvation and/or oil screen collapse."

Ditto to

what Mike F says. Also be aware that the crank throws and C/S prop capture sludge that can loosen up if a mineral engine is switched to ashless. As for seating rings, 75% power or more. My understanding is the combustion pressures get between the ring and piston and push the ring against the cylinder. Those pressures grind everything together.

Andrew
-4 started and sold
dreaming again