Confusion over oil choice for camshaft and then piston ring break-in

[Whiskey98]

Hi everyone,

First time posting and just looking for your expert advice regarding choice of oils for engine run-in. I appreciate this topic will have been done to death so apologies, however the answers I'm looking for seem to come from a range of sources, many of which seem to contradict each other.

I'm from the UK and am restoring a Triumph Herald, the engine is identical to that of a Triumph Spitfire. 1300cc straight 4, flat tappet cam with solid lifters. I am having the engine fully rebuilt by a shop I've used previously which has been rebuilding classic engines for decades so I am very confident with their care and attention to detail in building it. I don't want to mess anything up during the vital running in phase.

It's universally agreed that the very first start should consist of breaking in the camshaft using a very high ZDDP break-in oil (I'll be using Ravenol 20w50 mineral break-in oil that has a ZDDP concentration of 2500ppm). I will prime the oil system using a drill attachment to the oil pump, ensure everything is set up for a quick start, and upon starting immediately bring the revs to between 2000-2500rpm for 20 minutes, varying the speed between those 2 values as you go. Change the oil and filter once complete.


Okay, so this is the bit where I get a little confused. The next most important/tricky component to break in properly is the new piston rings to the newly honed cylinder walls. Again, it’s universally agreed that for the first few hundred miles, idling the engine and running it with no load should be kept to a minimum. I have read from numerous sources that a super high ZDDP concentration while essential for camshaft break-in, can actually hinder the correct wearing in of the rings by promoting glazing of the bores and is considered a necessary evil while during the first run as the camshaft takes priority.

What I'm wondering is once the 20 mins of camshaft break-in is complete, am I okay to replace the Ravenol oil with Valvoline VR1 20w50 (I’ll be using this after it’s fully run-in too) that has a ZDDP concentration of 1300-1500ppm, or will the camshaft require further breaking-in with the super high zinc Ravenol oil for a while? Also is the ZDDP content of the Valvoline adequate enough for breaking in the piston rings during those first few hundred miles?

As I understand it, the rotating components such as the crankshaft and big end bearings etc are of least concern, as long as there is good oil pressure and you don't exceed say, 4000-5000rpm during the first few hundred miles then they will wear in just fine. I believe this is right but please correct me if I'm wrong.

Finally, are there any more tips on how to drive initially for the best results in breaking in piston rings?

Many thanks

Peter

 

[MRC01]

The breakin procedures for vintage car engines are similar to aircraft piston engines. The cylinder bores are honed slightly rough to promote oil wetting and you want a little extra friction to scrub off the tips of that surface to promote ring/cylinder seating. That means use a pure mineral oil without friction modifiers and high cylinder pressures which push the rings into the bores. But don't let it get too hot, which can glaze the bores - if that happens they need to be rehoned. All else equal, high cylinder pressures mean hotter temperatures so don't let all else be equal.

In practice, getting high cylinder pressures without excessive heat means using full throttle while limiting the RPM and using higher speeds where you have more airflow & cooling (not 1st or 2nd gear).

The sign that the rings have seated is that oil consumption drops and stabilizes, and temperatures go down slightly. Depending on the engine, that may only take an hour or two. Or it could take longer... Once it's broken in, change the oil and you're good to go. You may want to cut the filter open & inspect the pleats for metal.

More on this topic:

 

[c502cid]

The only person I'd listen to here is the shop that built the motor. What do they say?

 

[ka9mnx]

What c502cid said...

 

[Whiskey98]

Spoke to the guy this morning and short answer is he's not too sure. He seems to go with the very old school method of not exceeding 50mph for the first 500 miles, avoid excessive idling, over-revving and labouring the engine, and change the oil after the first 1000 miles. No mention of any specialist oil, even for the first run. While he is a very skilled engine builder and been doing it for over 50 years, I feel as if a lot of what he said contradicts what I have read from numerous places online.

 

[ka9mnx]

Break in is mostly concentrated around the camshaft. As my understanding, piston rings are broken in, mostly, within minutes of the engine running. Beyond that, they will eventually seat themselves and no special oil is needed. Just easy driving until oil consumption slow or stops.

Your mechanic may be old school but so is your engine. I think his recommendation was OK.

 

[spasm3]

I agree with the high zinc needs for break-in. But if the cam is splash lubricated is 20w50 the best viscosity for this?
Plenty of 60's-70's engines with higher spring pressures were broken in on 10w 30 oils.

 

[Fair enough]

So we all have our ideas. Mechanic not too sure about it, means it’s good to go. The mechanic is going to start the engine and test drive it, probably is about ready to go as you get it. Change oil right away within 50 miles, then 200, 1000, and normal thereafter. I would use 5w-30 synthetic from the first start and after. Moderate over and over loading with coast down on the first drive 20-50 mph. No very easy throttle all the time. After that, normal use. Camshafts have springs loading them, bearings shouldn’t touch their surfaces together. I think it’s about seating the piston rings and cylinder walls, and flushing the debris away with oil changes.

 

[JAG]

P

Thread 'Driven Break In Oil 10w40'

Nov 25, 2024

Breaking in my flat tappet cam (Pontiac) very soon using Driven break in oil. The bottle says Do Not Add Additives.
Any real world experiences using this oil for flat tappet engine break in?

• PontiacHO
• Replies: 8
• Forum: Racing Oils/Engines/Cars/Teams/Drivers

 

[Nessism1]

Did the rebuild shop replace the cam and lifters? If not, you can dismiss all the cam break-in business. And even if they did, those engines are not a high performance American V8, where cam break in is critical.

It's been some years back now, but I rebuilt a Triumph TR6. I also had my TR4A's engine apart a time or two. And I don't recall any particular concern with cam wear.

I suspect that you are overthinking. Focus on the rings. Just drive in a normal "city" driving cycle. Accelerate away from stops, using a fair bit of throttle. Use engine braking to slow down. Vary engine load and speed, and you will be just fine.

 

[Aston4]

Spoke to the guy this morning and short answer is he's not too sure. He seems to go with the very old school method of not exceeding 50mph for the first 500 miles, avoid excessive idling, over-revving and labouring the engine, and change the oil after the first 1000 miles. No mention of any specialist oil, even for the first run. While he is a very skilled engine builder and been doing it for over 50 years, I feel as if a lot of what he said contradicts what I have read from numerous places online.

I go with this. The only new engines I have ever had trouble with, often BIG BIG trouble, were ones I tried weird BS internet break in procedures. Don't do it. Be a grandma. Every engine I broke in gently as your builder recommends, and as recommended by all owner's manuals for a century, lasted forever with zero oil consumption or noise even well after 200,000 miles. Straight 30 weight is what that engine was designed for, if it were me I would probably just use Castrol GTX 10w-30. Isn't "Castrol Only" stamped on your car somewhere?

Don't forget to re torque your head bolts. English cars. I miss them.

 

[Chris142]

I think different. I would leave the break in oil in it for a few hundred miles. During those few hundred miles I would get a good load on it. Not revved to the moon but spirited before the hone wears.