I've read a bunch of stuff about it. I'm almost done with the L98 B2L roller rebuild - essentially stock. I'm thinking running my normal synthetic motor oil, revving between 1500-2200 for the first 20 minutes. Change oil and filter. Run it easy for 1,000 miles or 15 hours. Change oil and filter again. Thoughts?

 

No. You want to run it medium-hard. Cylinder pressure seats rings and that's 99% of what you are breaking in. There shouldn't be any "breaking in" of the bearings, etc and being a roller engine the cam/lifters don't have any significant breaking-in to do.

I would put in a good quality break-in oil like Amsoil break-in, run it for about 20 minutes and then change the filter. As long as the oil still looks good I would then put 500 miles on it and change it out with synthetic and call it good.

GD

 

Agree with GeneralDisorder. Use a good break-in oil but don't use synthetic during the break in process. You're better off putting a brick on the pedal during break-in than running it easy, and letting it sit there and idle would be the worst thing you can do for it.

 

Just found this on BobistheOilGuy, Some heavy hitters in there. Amsoil's response is interesting. Enjoy.

https://www.bobistheoilguy.com/forum...l_Break-in_Oil

 

I find several guys ignorant in that post. They failed to even realize Nissan engines do not use roller lifters. They are flat tappet engines that have mechanical lifters with actual valve lash clearance.

 

With a roller cam Chevy engine there is absolutely no need to run the engine for cam breakin. Start it up, set the timing. Shut it off. Button it up. Take it for a drive. Give it heavy throttle but don't run it to redline. FWIW I break my engines in on Mobil One. GM started and factory filled even the LT1 engines with Mobil One.

 

We run Amsoil break-in on all our builds. Never had a single problem from doing so, and while you may (probably will) get away with running cheap non-synthetic (or probably even synthetic) on a roller engine for break in, we find that the potential cost savings from doing so is negligible - why cheap out? What are you going to save? $50 or less? How much of the total build cost is that exactly? Of course I'm an Amsoil retailer and so we have it on hand and thus it's the only non-synthetic I have. I also build mostly high performance import engines, which contrary to what most think (as Fast355 pointed out), are NOT roller engines. That's right - even a 2019 STi has no roller valve train. They are "shimless bucket" flat tappet engines and do need proper break in when we have 292 cams, stainless valves, and heavy springs.

GD

 

Know your engine's RPM range and run it through that range on a regular basis during break in. You don't need to be afraid of running your engine more or less normally as long as it's a quality build. Mineral oil first, than if it checks out, put yer syn in.

 

We use Driven BR 30 or BR 40 depending on the build. Flat tappet motors go 2200 to 2800, varying every few minutes between the low and high end of that range, for 23 minutes total. This is for both the cam and tappets and also for piston skirt/cylinder walls, since they're also lubed by windage. After the initial break in run, we take the vehicle on a drive up and down a steep grade. We alternate between moderate load uphill and engine braking downhill, this is how we seat the rings. Throughout the break in period, including the first 1000mi, we keep the revs below 3,500. After 1000mi, conventional or syn is up to the owner of the vehicle. I recommend Mobil 1 or Valvoline VR1. I run Mobil 1 in my own motor. Amsoil is also a very good oil. Used to sell it out of the shop and use it in customers' motors.

Race motors are an exception to the 1000mi break in rule. They get broken in on the dyno with the same cam break in for flat tappets and rev/decel for rings, then it's on to power tuning and measurement throughout their power band. No easy 1000mi break in for these guys.

 

How did the OEMs brake in new engines when the cars rolled off the assembly lines?...

 

Not sure how it was treated from the factory but both of my Titans got driven like I drive them. One had 6 miles the other 9 when I took delivery of them. WOT from the second they hit the on-ramp leaving the dealer. The current 383 in my Express van got the same treatment.

 

So after the not unexpected spirited debate here, I am going to go with:

1. run my normal oil
2. rev lower - let it warm up
3. rev through RPM range for 5 minutes
4. take it for a drive
5. 50 miles change oil and filter
6. run normally
7. change oil and filter at 500 miles and start normal maintenance cycles

 

50 miles is a long time to run the startup oil/filter on a DIY build IMO. I would be warming it up and checking things and then after that first 20-30 minutes you should at least replace the filter and cut it for inspection. Depending on the appearance of the oil - might need to change that also. 50 miles without a filter cut or oil change on a DIY build seems irresponsible to me. That's a long way and a lot could be going wrong and be unnoticed.

GD

 

Now that you mention it, it sounds like a lot. I suppose I will be watching the oil pressure and coolant temperature keenly at first. I'll cut it to 30-45 minutes.

 

Just use normal non synthetic oil and do a couple heat cycles to check for leaks and loose bolts. Double check everything is tight and engine is running as it should

then drive soon as possible. But if efi, tune needs to be worked some at the same time to make sure afr is not lean or rich. Way off fuel can hurt ring seal. Can detonate too depending so i would kee timing conservative for now.
Do not lug or baby it too much. Put a variety of ligt to medium loads on it at lower to mid level rpm like idle to 2500-3000. Let it coast down in gear to develop engine vacuum. Do short pulls to progressively higher rpm. 50% throttle, 4000 rpm or so and let it engine brake. Do a couple of those. Then move to 3/4 throttle to 3/4 of your redline. Couple of those then hammer wot pulls

you’ll be broken in way less than 100 miles lol

 

When I break in engines for customers, I drive them medium-hard, and if boosted I try to hit 5 psi or so..... for the first 100 miles. Then I go WOT.

We just started up a brand new Subaru engine yesterday at the shop. The break-in was moving it to the dyno bay and our tuner running it up to 80 mph on the rollers about 5 times before he went WOT and checked the startup map. He did 3 additional pulls at full power to dial in the tune. 353 AWHP, 369 AWTQ.

And that was it's break in. LoL. A 10 yard drive to the dyno bay and a couple rolls up to 80. Probably got a whole 2 miles on it before tuning. Runs like a champ.

GD

 

Yup, race motors break in at the track or dyno. Verify tune and let it eat. Street wouldnt be much different. Worked for me over the years

 

^^