4 stroke break in procedure?

thatsdax said:

Synthetic oil is not recommended.

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Synthetic oil - Wikipedia, the free encyclopedia


"The disadvantages of synthetic motor oils include.......

The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was, though. Many modern cars now come with synthetic oil as a factory fill....."

Presumably Japanese-made engines are the best machined, so break-in is less critical? I broke mine in on synthetic oil, and changed the oil after the first 20 hours as per the manual. As Staton predicted, power increased c27% once broken in.

I use Castrol 10w30 in my 4 stroke R/S motor. I agree 100% on the increase in power after break-in. I was really unhappy with it the first 100 miles but at almost 200 miles now it seems like a different motor. I don't know what the precent is but it has a lot more power now than when it was new.

Mifletz, how did you measure that 27%?

I've wondered about oil additives--graphite, Teflon, moly, and all of the various things that are sold under fancy names. They don't do much good in a car (or in a motorcycle since you'll end up lubricating your clutch), since all they do is plug up the oil filter, but in a small engine with a simple oil sump and "splasher"....might they help? I doubt they would be a good idea during break in, but once the engine has "set"...I would think anything "slippery" that would stay on bearing surfaces might be useful.

I'd be interested in hearing about anyone's experiences.

DaveM50 said:

I've wondered about oil additives--graphite, Teflon, moly, and all of the various things that are sold under fancy names. They don't do much good in a car (or in a motorcycle since you'll end up lubricating your clutch), since all they do is plug up the oil filter, but in a small engine with a simple oil sump and "splasher"....might they help? I doubt they would be a good idea during break in, but once the engine has "set"...I would think anything "slippery" that would stay on bearing surfaces might be useful.

I'd be interested in hearing about anyone's experiences.

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I've tried just about every treatment you can imagine and never found much difference in power or engine wear. I used them during my spectator dirt track racing days when ANY advantage was worthwhile.
We ran stock v-8's in torture environments where any improvement in wear would have quickly shown instantly and been copied by ever racer on the track.. Nobody I know uses them anymore unless they get it free. Microlon, Slick50, etc.
The single best thing you can do for four-stroke longevity is to break it in on conventional oil, then switch to a full-synthetic like Mobil1 or Amzoil or Lucas.
Synthetic oil was PROVEN to make engines last far longer in the insane conditions we forced on them.
I've had cars get the radiator popped first lap, and had the HEADS glowing red when the race was over 9 laps later. I swear on my life. Glowing RED HOT.
And the damn thing started right up after it cooled off.
Granted, it was much sloppier and clearly wounded, but it would have never turned over again with conventional oil.
I swear by Lucas synthetic in ANY four-stroke race engine.

One product I DO use is RESTORE, but it's meant for worn out motors, not prevention.

That makes perfect sense to me. I've been using synthetics in both of my motorcycles for as long as I've had them. And they just keep on going. Haven't had to do anything but replace plugs and check the valve timing and points on the '78 I've owned for eight years. Meanwhile I've gone through two sets of tires and a seat....but never a peep from the engine, clutch, or transmission.

I suspect that under the temperature conditions present in a small engine, anything containing teflon (which I believe Slick50 does) would break down. I do know that graphite and the like just plugs up oil filters, hence my question about small engines.

That said, if synthetic oil will stand up to racing conditions, there's no reason for any of us to even consider anything else.

Synthetic is pretty much designed for longer oil change intervals. If you change your oil quite often, there's really no point to running synthetic. A high quality conventional oil of the correct viscosity will do just as well.

I use nothing but Shell Rotella T 15w40 in my GXH50 clone.

Just want to make sure I've got the best oil film possible, as I will be running the engine fairly hard. As to oil changes, I believe most small engines call for a change every 25 hours after break-in. So, yes, a good quality conventional oil should be just find. On the other hand, the 99cc Predator takes 12 ounces of oil. So the difference in cost per change shouldn't be significant.

Relative to practically nothing, when I was growing up, my father would take drain oil from the cars and the tractor and filter it through a coffee filter into a large can. The filtered oil was used, variously, as chain saw bar oil, in all manner of small engines, and sometimes as two-cycle lubricant. We never fried an engine. My speculation is that used motor oil basically has worn out the detergents and some of the other additives in it, and so is more or less basic motor oil (with, hopefully, anything large enough to cause trouble having been filtered out. Since the average small engine just has a sump and a "splasher" to circulate oil It would most likely work just fine. Certainly it did in my experience.

My break-in procedure for a 4-Stroke is first start with petroleum based oil and ride it like you stole it for 5-10hrs. Then I start running a 50/50, pet/syn blend for 2 more 10hr. oil changes.

After that it's 100% synthetic oil and I do change it more frequently than not. My oil of choice is Maxima. My engines don't blow up or seize and I never baby them, I push them! I like to see what they can withstand.

Excess heat can destroy a new motor. The two main sources of heat are:

1. Friction. It is reduced during break in.

2: The EPA makes most motors too lean. They need to be re-jetted.

The worse case is to fry the oil in an OHC motor and destroy the cam bearings.

Break in OHC motors in slowly and watch head temps.

This OHV engine now has 53+ hours of pushing it hard on race tracks since brand new. It's gone from 10hp to over 20hp in the 3 years it's been racing.

It's a HF Predator 212cc that cost $99 + tax and now has about grand into it all told. I think it's finally broken in!

scotto- said:

This OHV engine now has 53+ hours of pushing it hard on race tracks since brand new. It's gone from 10hp to over 20hp in the 3 years it's been racing.

It's a HF Predator 212cc that cost $99 + tax and now has about grand into it all told. I think it's finally broken in!

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Such a sick looking bike. I get all excited every time you post pics of it haha