Question for everyone about breakin oil...

Not open for further replies.
May 27, 2002
Ocala, Florida
The subject of breakin oils was addressed on another web board that I was scanning and wanted to know what people here think about using a full synth oil during breakin?

Do you think synth oils will keep it from breaking in or have no ill effect on the engine? And why do you think it will or will not.

other question is, how many can tell me why the cross hatch pattern exists on the cylnder walls of an engine and how does that affect breakins'.


[ June 04, 2002, 01:04 PM: Message edited by: BOBISTHEOILGUY ]
I personally don't think synthetic oil will hurt the break in one bit. The rings on new engines are pretty much seated by the time you take delivery of a brand new car, and it's not as if synthetic oil is some super magic oil that makes an engine have no friction at all anyways.

There are more and more new cars each year that come with synthetic as factory fill and those engines break in just fine.

As far as the cross hatch pattern, I could be wrong but I always thought that this helped with the oil flow around the rings. Correct me if I'm wrong.
Oh, one more thing. As far as breaking in goes, it has always been my belief that you should always always always do the very first oil change around 500 miles. Getting the break in material out of the oil, and to get a fresh oil filter on there as well.

The only car that this might not work well on is the Volkswagens, as I hear they actually have problems when you drain out their special break in oil. If I owned one I would try and get a hold of that special break in oil, and still do an early oil change, and simply replace it with this oil. Or at the very least, I would change it's oil filter often in the first few thousand miles.
I agree. On my previous car I switched it out immediately after delivery after the same inquiries. I too believe that break-in in a factory car occurs in the first few minutes...and subsequent use of synthetic oil will not hamper any break-in the needs to occur. Can't comment on VW's and a custom made engine (engine shop) may require a break-in oil as the parts are not an accurate fit as factory... I always thought that the crosshatch cylinder wall pattern was to have a slightly roughened and hence friction induced surface for the rings to act against in order to sweep the oil away versus a mirror-smooth surface which would be more difficult to prevent blow-by.
I agree there is no harm in running a synthetic in a new motor. With the new metals used in todays engines the old method of break in is gone.

My wife has a new VW Eurovan, so I did some research to find out what was in their from the factory in Germany. It is not break in oil. It is a 5W40 full PAO synthetic made by Lubro Moly in Germany. Now Lubro Moly make an oil that is very dark grey in color with a lot of moly in it and it comes in a 10W40 only, and is not a synthetic. I'm not sure if their synthetics have moly in them or not.

Terry, have you ever tested Lubro Moly oils?
Although I don't use a synthetic, I agree with Johnny that it would do no harm in a modern engine. The manufacturer said to adhere to the normal change schedule (I use 4K miles) for the first change, and that's what I did.
I was told long ago that the #1 purpose of the cross-hatch pattern in the cylinder walls was to hold oil. Not a lot, of course, but more than a slick wall. Claimed that the oil was even more important than the slightly rougher surface in ring seating. True? Maybe not, but he *Was* one hell of a mechanic.

An old trick of industrial engine rebuilders was to "knurl" the piston skirts- engrave a cross-hatch pattern in them, done expressly for oil retention. They claimed it at least doubled ring life. True?

Synthetic oil for new breakin? Some manufacturers do that now, I just wonder how well it works- that is, if you wouldn't get an engine that was better "worn-in" by running dino or blend oil for that first few thousand miles. Does anyone have any real information on this?
I have to agree that the engine break-in occurs in the first few minutes after the first start, not in the first 500 miles as was previously thought. Therefore, using synthetic oil might extend the break-in for a few minutes, but that's irrelevant.

As far as cross-hatching, I thought it was to reduce friction between the rings and walls. i.e., the ring rides up and down the crosshatch, and dosen't "scrape" along the cyl wall. The oil provides a boundary layer, of course.
When I was still using Mobil 1, I would drive home from the dealer and immediately change to Mobil 1. Put many miles on those engines that I did that with. Certainly never had a problem with oil comsumption. According to Mobil, it is perfectly acceptable to do that.
Well, the break-in may be over for cars but I am still a bit easy with new motors, company cars, and vary my speed and floor it at speed then get off the gas to seat the rings. In the motorcycle world proper break-in is still a hot topic. Honda says 1500- 3k miles depending on who in the company you talk to. Some BMW's say from 5k to 10k!! They all say dino oil only until break-in then many move on to synthetic. Most are using 10-40 and I choose Mobil 1 for motorcycles at $8.00 a quart, ouch! Also doing the magnetic drain plug thing and magnets on the filter. By the way, I think I would also use Amsoil also but I got the Mobil for $ 3.00 at a close out. These are SG rated and have the JASO MA designation.
Chris: By the time they drive a new car off the assembly line to the back lot, load it on a transport truck, then unload it again, the rings are seated. The materials they makes rings out of today are pretty good.

You stay with that Mobil 1 motorcycle oil. That is some good stuff. My next door neighbor has a R100 (I think that's the model) with 98,000 miles on it, and another friend has a Harley that he uses the Mobil 1 20W50 V-Twin motorcycle oil in. It has 60,000 miles on it. Yes sir, that is some good motorcycle oil.
Don't ignore the break-in oil requirement for equipment other than cars! My John Deere tractor manuals specifically state that their tractors come new with break-in oil and they state not to use their Plus 50 (synthetic blend) until after a good break-in period. I have read stories of people putting Plus 50 into rebuilt John Deere engines and they had to tear the engines down after a few months and rebuild them again! Break in oil still exists for some applications.

If new car engines are built so "precise" from the factory and the manuals say to do the first 0il change at the regular interval, is this 500 mile oil/filter change idea just a remnant of the old ways? Is it really necessary anymore?

I don't believe the 500 mile oil change will ever be unnecessary, even if the rings are seating quickly. There will still be other wear materials in the oil from other parts of the engine, along with the fact that your brand new car's oil still could be in rough shape, due to frequently having the engine started and shut off without being warmed up. I'd love to take an analysis of that first oil change and see how rough shape that factory fill oil is. They don't exactly use the highest quality of oils in most cars either, just the cheapest bulk stuff the factory can find (with the exception of those engines that come with synthetic of course)
I just could not leave the assembly compounds and metal in the engine of my personal vehical. The first dump on many motorcycles is 600 miles but many do it at 100 first. I did it at 300 as service manager told me on the side is best. Another $15.00 is not a big deal on a $8,000 bike that spins up to 13k.
Big trouble with Chev LS1's here. Mates HSV R8 just had bores honed and new piston/ring kit fitted. Mobil 1 10W-30 factory fill. I would use a high quality non-friction modified dino for maybe 3000 miles, get those rings seated properly and no 'glazing' IMHO.
I had the idea that knurling the piston increased the diameter of the piston so that it fit tighter in the cylinder. Rather than buy oversize pistons you increased the size of the old ones.
Originally Posted By: maly
I had the idea that knurling the piston increased the diameter of the piston so that it fit tighter in the cylinder. Rather than buy oversize pistons you increased the size of the old ones.

Knurling a piston or a valve guide is a band-aid. It will probably get you fixed, but it will not be a long term cure. This "fix" was done when cars were lucky to get to 70K miles before an overhaul, not the 300K engines that we commonly see today.
Cross-hatching the cylinder wall was for the old cast iron or chrome piston rings for oil retention. The cylinder walls for a good moly piston ring should be smooth.
There is, however, a piston manufacturer that puts a "knurl" on their pistons for oil retention. They do not do it to increase the diameter of their piston.
I always change break-in oil at 1000 miles on cars. 20 hours on a boat and 100, 500 and 1000 on a motorcycle (Harley). You would not believe the visible debris at 100 miles on a Harley Twin cam engine. I should have strained my latest one's FF in a white coffee filter and posted a pic of it. Huge pieces of metal at 100. Smaller ones at 500 and clean oil & magnet at 1000. I always use synthetic oil and after about 8 engines of varying types none have ever consumed much oil.

I am very sold on the idea of changing FF out early.
Not open for further replies.