Engine Break-In Procedure - New vs. Rebuild

[Shazaam]

The answer to how to break-in an engine, and whether to use a synthetic oil during break-in, is different for new engines and rebuilt engines. What the engine manufacturers do and recommend for a new engine break-in should not be construed as the best solution for a rebuilt engine. Here’s why.

The manufacturer controls the complete quality assurance and quality control process: design, fabrication, build, inspection and testing. The overall result is not necessarily better than can be achieved by a custom engine builder, just more consistent.

So when a manufacturer first fires-up each new engine on a test stand, they know from experience (and monitoring each engine’s exhaust oil combustion products) that the piston rings will seat properly before the engine leaves the factory.

Every Ducati is run-in for ten minutes or more on the dyno using a prescribed rpm and temperature sequence. Many manufacturers including Ducati, Porsche, Mercedes-Benz, Corvette, Viper and Aston Martin do their initial fill with a synthetic oil, and piston wall glazing is simply not a problem for them.

The piston rings seal is mostly complete after this initial test run. The follow-up part of the break-in (that you read in your Owners Manual) has little to do with piston ring sealing. It’s meant to accommodate the time it takes for normal wear to occur to thousands of mating parts like bearings and gears, that will happen regardless of the type lubricant used. It’s particularly important to change any lubricant early, and often, to remove the resultant wear debris.

However, when you rebuild an engine you can introduce a number of variables (that affect glazing) that are different from a new engine such as piston ring material, clearances (that affects ring pressure on the wall) and cylinder wall surface finish. Also, not all engine re-builders have complete, accurate control over their cylinder-wall finish and ring type like the manufacturers.

Cylinder wall glazing occurs when the engine is run at power levels too low to produce temperatures high enough to expand the piston rings sufficiently to prevent a film of oil being left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates a condition commonly called glazing. When this happens, the ring break-in process stops, and excessive oil consumption can occur. Excessive glazing can only be corrected by removing the cylinders and re-honing the walls.

The build quality of engines 25 years ago probably contributed to the controversy that somehow synthetic oils are too slippery for break-in and that than conventional oils should be used.

So what do the oil manufacturers say?

According to a Road & Track article a few years ago regarding the use of synthetic oil during break-in, Mobil’s position was that engines break-in just fine on synthetics, and that any wear point in the engine significant enough to be an interference, and thus susceptible to rapid wear, would be a wear point no matter what lubricant is used. Redline on the other hand, recommended a mineral oil for break-in. They say that in their experience, occasionally a rebuilt engine will glaze its cylinder walls when initially run on Redline synthetic, so by using a mineral oil for 2,000 miles, verifying there is no oil consumption, and then switching to the synthetic, glazing is eliminated.

In any event, for a rebuild, you shouldn’t use an Owners Manual-style break-in period. You need to reproduce the Ducati factory dyno runs to avoid cylinder glazing. One way is to monitor tailpipe hydrocarbons to see when they drop during dyno runs. The other way is to ride it like you stole it.

[Maximus-Speedicus]

Thank-you Shazzam.. yet another well written and very informative post.

Can you tell me please, when I was younger we would use a straight 30 weight oil for running in, about 600 miles before going to regular oil useage. Can one still adhere to this idea with rebuilt motors?? Would there be anything to gain or lose by doing this?

Thanks


In accordance with the prophecy...


Mal

[Shazaam]

It helps. The underlying principle here is if the oil film is too effective, it will hold apart mating parts, even ones that have high surface roughness. If this happens, the piston rings don’t bed-in successfully, and you get cylinder wall glazing. So if you use a lighter-weight mineral-based oil early on, you help the break-in process.

Synthetics have a better surface film and tolerate higher temperatures better so they tend slow down the break-in process.

So for a rebuilt engine I’d run run a track day (or a few hundred miles in the canyons) on a 30 weight mineral oil, drain it and refill with a good 50 weight synthetic.

For a new bike right out of the crate, the piston ring break-in was finished at the factory and the sump filled with a synthetic, so you’re good to go.

[The other Andrew]

Shazaam. First I want to thank you for all your postings. Anything you say appears very informative and valuable to people like myself. You are a super smart person. It's amazing. I am grateful you're on the team.

As a recent owner of a new '07 Ducati 1098S bought with 180 miles, I have fairly followed the manual. What I mean by that is that I kept the RPMs between 5500-6000 for the first 1000km but did it commuting on the freeway instead of up and down revving in the canyons like the manual encouraged.

My break-in questions are:
1. How would I know if the previous owner didn't punch it for the first 180mi?

2. Is it bad that I rode it from 180mi to the 1000km point by fwy commuting?

3. Should I really be nursing it and this sensitive (After recently viewing websites with people insisting to open it up for proper engine break-in, and not baby the engine like the manuals all say)?

[Shazaam]

I'll forgo the technical answers.
Stop worrying, just ride it any way you like and enjoy it.

[jboothe]

Originally Posted by Shazaam

The other way is to ride it like you stole it.

From my very humble experience, that's the best way ro break any engine in. Change the oil at a few hundred miles or so and repeat and then start following the manufacturer's recommendations. However I will say I tend to change my oil in the Hyper a lot more often than Ducati recommends. It sees a lot more time with my right wrist rotated all the way down than it should and I figure it is 100% reliant on the oil for cooling as well as cleaning and lubricating. Can't hurt and makes me feel better since I bought the thing to ride the crap out of it not just look at it...