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Break in Oil



I was reading in "Sport Truck" magazin, they were buiding a big block motor. All things were pretty normal until I read the part where they took the crate engine, put it on the dyno, here comes my question, broke it in before any tests were done, with "30W non-detergent oil" and then chaned it to 20W50(brand omitted by me because, it ain't my brand). Has anyone ever done this with break in oil. I have always used what I was going to run in the engine. My questions are 1. Has anyone done this. 2. Has anyone ever heard of this and 3. Why would you do this? If none of this applies, how do you break in your new engines?.........Steve
Engine Breakin Period


This is a very interesting subject, I'll be listening to the responses you get.

I've owned a number of new vehicles, 4 Corvettes in this group. I bought them from a dealer that was about 100 miles from where I used to live. I varied the speed (rpm) the first 500 miles or so, run at 50 mph for a couple of minutes the up to 85 or 90 for a few miles. Basically I was all over the rpm range during the first 500 miles. Then I changed the oil and ran "my favorite" brand of 10-40. I ran Brainard International with only 800 miles on my '84. I've never had any problems.

A mechanic buddy back in 1965 when I rebuilt my first engine pointed out the milky looking stuff in the engine, He then LECTURED me about using ADDITIVES and NOT to use Parafin Based Oils. He got my attention since he was the resident Gear Head in my home town, I still live by his words :D

Break in oil

Hi Steve,

I thought you were an old guy. Back when cast iron piston rings were the norm for rebuilds this was a common practice. Cast rings are hard to seat and the non-detergant oil helped this. I guess it allows more friction. You would run this break in oil for 500 to 1000 miles then drain and change to whatever you normally use. Hopefully, but not always, the rings took a seat and sealed. Yes, I have done this.

With the Moly rings this changed. They seat almost immediately and don't require the extended break in period. You should be able to drive your car normally after just a couple hundred miles.

I would think that the non-det oil would also help in running in the cam and other new parts. Since you are going to drain it shortly you will save a few cent per quart. You should always change your oil in a new engine before 500 miles to get any junk out from assembly and break in.

Any engine in a new car and many custom crate engines don't require any break in period as they are run in before installation in the vehicle or shipping, in the case of crate motors. As far as using non-det oil to break in, it doesn't hurt anything and can possibly help. You aren't using it long enough for any contaminates to build up inside the engine.

I suppose it is your choice as to what you are comfortable with. I know if you are going to run synthetic oil it is necessary to break in with conventional oil as the synthetic won't allow enough friction to seat the rings.

Bud, I use to think that you ran the new motor during break in as you said. Now my engine builder say's "Break in the cam at 2000 RPM's for 20 min, and then give it hell" (I haven't been able to do this though,too old fashion). I am a strong believer in changeing the oil shortly after break in, be it 500 miles or after to 20 minute cam break in. I had just never heard of using non detergent oil for this process. The only person I ever knew to put non-detergent oil in a vehicle was my grandpa, and he used it in the ole 48 GMC(That I still have) and the 51 Chevy car. Tom, I too have heard that about synthetic oils,......Steve

[Edited by ssvett on 02-16-2001 at 05:49 PM]

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