Synthetics and breaking in engines

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FCD

FCD

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Ok so a while back i posted a thread asking if it was a myth that you can't use synthetics for breaking in an engine, and most people said it was true that you should use a conventional oil for that and most engine builders seem to agree, but why is it that you shouldn't use them for breaking in an engine? i've heard things like it doesn't let the piston rings seat in etc... do synthetics really do too good of a job lubricating or?
 
Modern engines are designed better, built to much more accurate dimensions and better quality control and more consistent materials and assembly then in years past.

A traditional break-in is not necessary. Just get in and drive. If you're worried take it easy for a few days and use come common sense.

Today it's common for an engine to outlive the rest of the car. A hundred thousand miles used to be a long life for en engine. Today it's the time for the first service other than oil and filter changes.
 
I did it on about 20 new cars over the years.
No big deal. Just did the same on a F350- of course it comes with SS anyway
 
Originally Posted By: FordCapriDriver
do synthetics really do too good of a job lubricating?


Definitely not. Maybe back in the day before grp III's came on the scene,maybe that's where this came from? 99% of current "synthetic" oils are conventionals so maybe that's why this has turned into a modern urban legend and or myth.
 
This break-in story comes from the earliest day of synthetics that were based entirely on diesters. The high levels of polar diesters (over 80%) competed with the ZDDP and caused wear in some engines with rocker arm followers. The ZDDP would win the competition, as the wear only occurred during the first few hours of a Sequence V engine test.

This wear problem was only noticed in laboratory test engines which were broken in with the ester test oil. Consumers did not have the problem as all new engines were factory filled with conventional mineral oils for break-in, and the ZDDP had a chance to lay down its protective layer.

Modern synthetics are based mostly on non-polar hydrocarbons with little or no esters for balance, and are fine for breaking in a new engine, as evidenced by the fact that many engine builders factory fill with synthetics.

Tom NJ
 
Originally Posted By: FordBroncoVWJeta
Honda and VW would say otherwise....


As for VW, perhaps now they do. But in the 90's. an old German guy at one of the original Buffalo dealerships said not to use syn during break-in because of "high speed glazing", IDK...
 
Big difference between a new factory built engine and one rebuilt in a shop.
I remember someone on another forum who worked in an engine factory say that a new engine gets filled with a special break-in oil for initial start-up and testing.
That oil is drained and re-used on other new engines.
The engine is installed into the vehicle and refilled with whatever it goes out the door with.
So those first critical minute minutes of run-in are done with something the public never sees.
 
I'm not sure I have ever seen evidence that there is some super special oil used for break-in.

I can tell you this though, back in the late 80s or early 90s I rebuilt my Mazda 626 engine and put M1 5W-30 in from the start. It broke in just fine.
 
You can get full blown FS oil cheaper than most top tier conventional oils.
A six pack of FS Kendall GT-1 shipped for $22- Sure you can get [censored] no name oil cheaper but I tried some of those- never again. To each his own I guess.

Originally Posted By: rideahorse
It tells me that syn oil is just a marketing gimmick. It is no better or worse than dino oil. It just makes your wallet a lot lighter.
 
So it used to be somewhat true in the past but not now?
I have heard of a guy that rebuilt his Ford 1600 Kent OHV engine and used Mobil 1 15w50 since the start and after the usual time it takes for an old school engine like this to break in it apparently still burned lots of oil and smoked badly, this is just anecdotal evidence though...
 
Originally Posted By: FordBroncoVWJeta
Honda and VW would say otherwise....

Honda emphasized not using synthetic oil in S2000 until after 10k miles. Factory fill was dino and they said synthetic should not be used until after 2 oil changes.

I don't know about newer Honda.
 
As stated, you do not want any sort of chemical competition for the AW package on new metal surfaces.

Modern engines that are factory filled with synthetics are all either OHC or Roller Cam'd.

You rebuild a flat tappet motor (older car, truck, boat or tractor) and you use good dino oils with decent add-paks... You don't and you will be doing it again.

The thing becomes more involved when you get to Iso-Syn and severely hydro-cracked dino oils... They are as good as many synthetics (99% are a blend anyway), but work OK for break-in
smile.gif


And then again, it all depends on what cam lube you used during assembly... If you used Crane Cam's goo, or Sta-Lube moly paste, you should be good to go with most name brand oils. You use the red slime from Comp Cams and let the motor sit for 24 hours and you may be praying there's enough left to do its job (it runs off)...

As usual, it's the combination of parts at hand and work-flow that will determine if you need something special... There are rebuilt engines sitting in warehouses for months that will have to fire and go. For those I'd use best quality dino oil for fist 50 hours or so. If they live that long, you can pretty much put anything you want in there and drive on
laugh.gif
 
Originally Posted By: HTSS_TR
Originally Posted By: FordBroncoVWJeta
Honda and VW would say otherwise....

Honda emphasized not using synthetic oil in S2000 until after 10k miles. Factory fill was dino and they said synthetic should not be used until after 2 oil changes.

I don't know about newer Honda.

Most newer Honda engines are sold with 0w20 oil in them. I'm not sure if it is full synthetic or a blend.
 
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