pagiven@drutx.UUCP (GivenP) (12/02/85)
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I have heard from more than one source now, that before using syn-
thetic oil, the engine should have 6K to 8K miles so the engine
could properly "break in," "seat," or "become seasoned."
What exactly do these terms mean, anyway? Is it necessary for an
engine to wear out to a certain degree before the process is stop-
ped with a changeover to synthetic oil?
It would seem to me that as an engine wears, tolerances become
greater, that is, parts fit more loosely and thereby no longer pro-
perly seal. For instance, oil leaks past rings into the combustion
chamber, oil leaks past valve guides, gasoline and burnt byproducts
blow past the rings into the oil, tappets start making noise, etc.,
etc., all to a greater degree in engines that have more wear.
I had 400 miles on my 1981 Buick when I changed to synthetic. It
now has 95K more miles on, with no increase in oil consumption. It
uses about 1 quart every 4K to 5K miles now as it did when it was
new. Should I be concerned that my engine was never properly
"broken inIIIe
BTW, what is the difference between an "engine" and a "motor?" I
always understood a motor to be an electric engine.
-----------------------------------------------------------------
Paul Given {ihnp4, houxe, stcvax!ihnp4}!drutx!pagiven
AT&T Information Systems Laboratories
11900 N. Pecos, Rm 1B04, Denver 80234 (303)-538-4058
----------------------------------------------------------------dennis@vrdxhq.UUCP (R. Dennis Gibbs) (12/03/85)
In article <746@drutx.UUCP>, pagiven@drutx.UUCP (GivenP) writes: > I have heard from more than one source now, that before using syn- > thetic oil, the engine should have 6K to 8K miles so the engine > could properly "break in," "seat," or "become seasoned." > > What exactly do these terms mean, anyway? Is it necessary for an > engine to wear out to a certain degree before the process is stop- > ped with a changeover to synthetic oil? > It means that when an engine is brand new, internal parts (seals, piston rings, etc.) do not fit well together on a microscopic level. It takes some time before these parts can "wear" down so that they mate perfectly with their corresponding parts. Until this break-in has occurred, it is not uncommon for a brand new engine to consume more oil than normal. As the engine is used, the surfaces "wear in", giving a closer fit and a better seal. This is why most owner's manuals usually have a paragraph suggesting that the oil level should be checked frequently during the break in period. > It would seem to me that as an engine wears, tolerances become > greater, that is, parts fit more loosely and thereby no longer pro- > perly seal. For instance, oil leaks past rings into the combustion > chamber, oil leaks past valve guides, gasoline and burnt byproducts > blow past the rings into the oil, tappets start making noise, etc., > etc., all to a greater degree in engines that have more wear. > > I had 400 miles on my 1981 Buick when I changed to synthetic. It > now has 95K more miles on, with no increase in oil consumption. It > uses about 1 quart every 4K to 5K miles now as it did when it was > new. Should I be concerned that my engine was never properly > "broken in?" > > Paul Given {ihnp4, houxe, stcvax!ihnp4}!drutx!pagiven Synthetics have a higher film strength and lower coefficient of friction than do regular oils. Thus, if synthetic is installed in a brand new engine, it may impede the break in process, by not allowing the internal parts to "wear" down so that a closer fit and a better seal (for oil control) is achieved. Every engine (even the same brand and type of engine) differs in the length of the break in period. Some engines need only a couple hundred miles to break in properly, while others need a few thousand. Your experience with your Buick indicate that the engine was broken in sufficiently when you put the synthetic in. I don't think you have a thing to be concerned about, an engine that has 95K miles and still gets 4 - 5K miles to a quart of oil is very good indeed. The reason I recommended a break-in period of 6 - 8K miles is to allow even the most "stubborn" engines to break in completely. Since there is no way to really predict or name an exact mileage figure for break in, it is safer to assume the engine takes several thousand miles to break in. Also, at 6 - 8K miles, the engine is still new enough so that it is unlikely that significant carbon deposits will have built up. Dennis Gibbs
rct@occrsh.UUCP (12/06/85)
/* Written 1:57 pm Dec 2, 1985 by pagiven@drutx.UUCP in occrsh.UUCP:net.auto.tech */ /* ---------- "Syn Oil and Breakin" ---------- */ I have heard from more than one source now, that before using syn- thetic oil, the engine should have 6K to 8K miles so the engine could properly "break in," "seat," or "become seasoned." What exactly do these terms mean, anyway? Is it necessary for an engine to wear out to a certain degree before the process is stop- ped with a changeover to synthetic oil? ... /* End of text from occrsh.UUCP:net.auto.tech */ The mating surfaces of the piston rings and the cylinder walls in a brand-new (or freshly overhauled) engine are such that the piston rings do not seal the combustion chamber as well as they will after a "break-in" period of several miles (depending on driving style, piston ring material, etc.). During this "break-in" period, the friction between the rings and the cylinder walls serves to smooth out to some degree most of the surface irregularities, resulting in slightly higher compression and lower oil comsumption than when the engine was first put in service. This is why most automobile owner's manuals will caution that some oil consumption during the break-in period is to be considered normal. The debate rages on as to what constitutes a proper break-in period for new cars. The facts as I understand them imply that most new car engines are past the critical portion of the break-in period (the first few hours of run time) by the time the new car is delivered to the customer. This would explain the low (practically non-existent) oil consumption experienced by most owners of today's new cars during the first 5,000 miles. To answer your question about using synthetic oils in new cars: Running the oil that came with the car until the first oil change is generally a good idea. When to change the oil? I disagree with the 7,500-mile oil change intervals recommended in many owners manuals and regard them as too long to properly preserve an engine past 100,000 miles. I've had good luck with a 5,000-mile interval, but this depends on many factors relating to driving style and environmental conditions such as climate, dust, etc. I recall reading an article about a cab driver back east that had over 1,000,000 miles (NOT a typo) on a `50's vintage Cadillac (original engine, never overhauled)! He changed the oil every 100 miles though... --Bob Tracy ...!ihnp4!okc_5b!occrsh!rct
mikey@techsup (12/10/85)
A newly manufactured engine has a lot of 'machine' edges and surfaces that don't quite fit right. As a matter of fact, a new engine uses more oil than after it is properly broken in, usually. Rings don't seem to always seat until a few hundred miles, and there are also probably a lot of other cases where the parts 'wear to fit' and are actually better after a short 'run in'. mikey at bbimg trsvax!techsup!bbimg!mikey