Engine Break In Oil

[GlennSullivan]

After a long 18 month build (with a little 3 month delay at the end for reconstructive shoulder surgery and recovery), my car is finally running.

How long do you run break in oil for? In my previous 2 engines, we drove the car for 25 - 50 miles changed the oil and put it the car on the dyno.

In my opinion, neither of those engines achieved the level of ring seal that they should have had. This time around, I'm planning on a longer break in period for the engine, possibly 400 miles. This will also provide time for the clutch to wear in before the car goes on the dyno.

The question is, (there had to be one in here somewhere, right) can I, (should I) keep the break in oil in the engine for that long a period or should I change after the first 100 miles.

[rel3rd]

Hi Glenn,

I'm no engine builder, but the way I have done it for at least a half dozen engines that I have built (for myself) is this...

I run cheapo Pep Boys brand oil (or break in oil, if you choose) for initial start-up and first running/idling heat cycle, then drain it and replace with the same grade cheapo oil, but decent (Wix, Purolator, Motorcraft...anything but Fram) oil filter. Run it for a week, driving it everyday since I was glad to have it running again, lol...

Then drain and replace with whatever oil you plan to run normally.

I do try very hard to keep rpm's varied whenever engine was "fresh", and also "tried" to stay away from max rpm's, although I NEVER totally "baby" a new engine either. I think that does more harm than good. Basically, once I know that there are no leaks or other bugs to worry about, I drive it kinda hard without going all out, or flat out abusing it. Enjoying the power without winding her all the way out. This has always worked great for me and I have never had any issues like ring seal, or lower than expected performance out of an engine that I "broke in" this way, whether it was an old small block Chevy with flat tappets, or a faithful 5.0 based blower engine.

If memory serves me (as it was NINE years ago) :drop:, I put about 180 spirited miles (in a week) on the old BarneyCar before heading to Cecil for Spence to teach/help me start getting the WOT fuel and timing dialed in. That engine, which I built in the laundry room 20 feet from where I sit typing this, never burned a drop of oil and ran a new best almost everytime I raced it. :-D

Good Luck with the new setup Glenn. :thumbsup:

[GlennSullivan]

Thanks Bob

[gadget73]

Make sure you do some WOT and decel cycles as soon after initial startup as you can. That will help seat the rings better. Babying the car will just polish the hone marks down, preventing the rings from ever fully seating. The hard throttle followed by a decel will give you a cycle from full pressure to full vacuum, both of which push the rings into the cylinder wall so they'll seal up properly.

I think I did my first oil change around 300 miles, then 1000 miles, and ever since I've been on a 3000 mile cycle.

[Ourobos]

I am on about 400 miles on my fresh 351w build, plan on changing it next free time I have, going to dino oil again for about 1000 miles, then full synthetic.. I think you'll be fine waiting 400 miles or so, mine is sealed up tight, and the oil is still really clean.