Classic vs Modern Engine Break-In

[camrydriver111]

I see a lot of topics on engine break in, but not a lot on the differences on classic vs modern cars.

Modern cars are filled with fully formulated synthetic at the factory and driven off the assembly line.

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.

Why are modern cars able to do this, but classic cars can't? Is it the surface finish of the cylinder walls? Is it special materials like Alusil or Nikasil? If break in is the final step of the honing process, do modern engines just have this step already completed? Is it the assembly lube they are using?

Is it actually beneficial to dump the factory fill? If you run the factory fill for the full OCI, maybe the extra metal have an abrasive effect and mimick the effect of break-in oil?

 

[buster]

I'm not sure if there is a difference between breaking in a classic vs modern engine. The first 20-50 miles or so is when rings seat. It doesn't take an enormous amount of pressure to do so either. Varying rpms, generally no higher than 4k, is sufficient enough to break in the engine. You don't want to baby it or WOT to redline either. Basically city type driving is best. Avoid extremes.

Good question about the FF. I know Honda remains pretty adamant about keeping their oil in the engine until the first OCI is down to 15% of the MM. I'm not sure what their reasoning is other than the FF oil does contain a good dose of moly.

 

[kschachn]

I see a lot of topics on engine break in, but not a lot on the differences on classic vs modern cars.

Modern cars are filled with fully formulated synthetic at the factory and driven off the assembly line.

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.

Why are modern cars able to do this, but classic cars can't? Is it the surface finish of the cylinder walls? Is it special materials like Alusil or Nikasil? If break in is the final step of the honing process, do modern engines just have this step already completed? Is it the assembly lube they are using?

Is it actually beneficial to dump the factory fill? If you run the factory fill for the full OCI, maybe the extra metal have an abrasive effect and mimick the effect of break-in oil?

How old? I never had a problem with my 1982 Mazda engine, nor with an early 90s Honda. It sounds like Internet nonsense to me, especially considering the synthetics of today are nearly all Group III which is more or less chemically identical to Group I or Group II base stocks.

And that question about dumping the factory fill early, there are tens if not hundreds of long threads on that topic. In fact there was another one just recently.

 

[BMWTurboDzl]

I see a lot of topics on engine break in, but not a lot on the differences on classic vs modern cars.

Modern cars are filled with fully formulated synthetic at the factory and driven off the assembly line.

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.

Why are modern cars able to do this, but classic cars can't? Is it the surface finish of the cylinder walls? Is it special materials like Alusil or Nikasil? If break in is the final step of the honing process, do modern engines just have this step already completed? Is it the assembly lube they are using?

Is it actually beneficial to dump the factory fill? If you run the factory fill for the full OCI, maybe the extra metal have an abrasive effect and mimick the effect of break-in oil?

My guess.

Greater degree of manufacturing precision,
Roller cams
Changes in metallurgy
Running-in at the factory during assembly.

I haven't seen a UOA which performed a particle count on the number and size of various particles found in a sample to confirm whether the initial wear was abrasive. There's this thinking that high initial wear numbers in a UOA are actually contributing to engine wear.

If you think about it, for the last 20+ years can go for 200k-300k miles with simple oil changes when back in the 1980's people would look to dump their cars at 100k miles because of high oil consumption.

 

[ATex7239]

I'm not sure if there is a difference between breaking in a classic vs modern engine. The first 20-50 miles or so is when rings seat. It doesn't take an enormous amount of pressure to do so either. Varying rpms, generally no higher than 4k, is sufficient enough to break in the engine. You don't want to baby it or WOT to redline either. Basically city type driving is best. Avoid extremes.

Good question about the FF. I know Honda remains pretty adamant about keeping their oil in the engine until the first OCI is down to 15% of the MM. I'm not sure what their reasoning is other than the FF oil does contain a good dose of moly.

Anecdotal: Years ago I was regularly working as a vendor at a major auto manufacturing plant. While working around the facility I noticed that periodically one the vehicles would be taken straight off the line outside for what appeared to be 0-60/60-0 test. WOT from full stop then an immediate hard brake to full stop. I witnessed this event over many months and many vehicles.

I once owned one of the same vehicles made at that specific plant. Never had issues with the engine. And who’s to say mine didn’t have the same thing happen to it. This was one of the contributing factors that made me realize how much I was probably overthinking break in/break in oil changes on modern vehicles. I run the intended interval and just drive like normal from day one.

 

[thastinger]

Classic cars can certainly do this, they are just using the wrong machine shop and piston ring combo.

 

[wpod]

Engines can not help but to break in despite the oil used.

 

[TomYoung]

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.

You are asserting this, or simply stating as though it is accepted, common knowledge. I dispute that and would note that most of the cars on the road and most rebuilds have probably never seen anything other than synthetic oil.

 

[930.engineering]

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.
Why are modern cars able to do this, but classic cars can't? Is it the surface finish of the cylinder walls? ....... If break in is the final step of the honing process, do modern engines just have this step already completed? Is it the assembly lube they are using?

I don't think local machine shops use the same advanced multi-million dollar tech huge factories use.

Is it actually beneficial to dump the factory fill?

We had that discussion a thousand times. I prefer to do it with any car.
.
.

 

[vpr5703]

I've heard that break in differences *CAN* be attributed to the different metallurgies used in the rings and cylinder walls. Older materials might want/need/whatever to be broken in differently (hard break in vs varied running vs light loads, ect....) because the hardness of the rings and cylinder walls change how the rings seat.

I'm not an engine builder or anything, but it makes sense that more modern materials might change the break in process or possibly negate it, depending on how the OEM builds the engines. Dunno for sure, though.

 

[Nicasio]

I see a lot of topics on engine break in, but not a lot on the differences on classic vs modern cars.

Modern cars are filled with fully formulated synthetic at the factory and driven off the assembly line.

If you do this after rebuilding an old engine, the piston rings won't seal properly, so you need to run a break in oil, or at the very least conventional oil. Synthetic oil is actually too good at preventing wear.

Why are modern cars able to do this, but classic cars can't? Is it the surface finish of the cylinder walls? Is it special materials like Alusil or Nikasil? If break in is the final step of the honing process, do modern engines just have this step already completed? Is it the assembly lube they are using?

Is it actually beneficial to dump the factory fill? If you run the factory fill for the full OCI, maybe the extra metal have an abrasive effect and mimick the effect of break-in oil?

I’m wondering this as well, but I’d dump the factory fill much earlier

 

[930.engineering]

.
Like many if not most forum members I've watched hundreds of UOAs (very first oil change).
Every single UOA revealed more or less always the same: elevated amount of wear metals
like Fe, Al and Cu, to a lesser extent Cr and V. Larger particles can be found between the oil
filter's pleats - on every very first oil change.
In other words: all modern engines behave basically just the same as ones decades before.
And you want to get rid of these (elevated amount of) particles. At least it's desirable to get
them rid of them.
.

 

[BigCahuna]

Many years ago when I was in High School 1971 to be exact, our auto shop teacher set it up so we could tour the GM Cadillac assembly plant in Linden NJ. The tour started where the started building the cars from the very first piece of sheet metal. The tour lasted approx 3 hours. During that time we saw them install every part of the car including the engine. They fueled it up and started them. They ran them to warm them up a few minutes, before they pulled them onto the dyno. Where every part of the car and engine assembly was tested. They ran them harder than I thought they would. They took those brand new engines up to 120 mph for about a minute. Making sure they didn't blow, and that the trans shifted like it was supposed to. Then drove them "like they stole them", to the next test station. GM must have had faith in their product to do that to them, which meant that was how to break them in properly. Then after a customer bought that car, they would tell them to drive it easy for the first 1k miles or so. And remember, that was back in the day when mineral oil is all there was. I'm sure it was nothing special bulk oil, bought at the lowest price they could find. The "Esso" refinery was less than 3 miles from the plant, so I'm betting that's what they were using. And today, some vehicles come from the factory with synthetic oil in them. If you ever wondered why your brand new vehicle has 5-10 miles on it while on the showroom floor, the miles add up quick at 120 mph.,,,

 

[nascarnation]

Back in the day (1960s) at Chevy Tonawanda engine they did the initial run-in ("hot test") at the engine plant on gaseous propane. They didn't put a carb on the engine until the assembly plant. The old joke was take it right up to 5000 rpm and if nothing comes flying out, ship it!

The Oldsmobile Quad 4 (1990s) had no hot run at all before installing in the car. They ran the cylinder head assembly and the complete engine on electric driven dynamometers ("cold test") and measured parameters including vibration and torque signatures and the computer compared them to "known good" data. Leak integrity was done via applying vacuum and measuring the decay rate.

Not sure what the industry is doing today.