Interesting stuff, though I don’t think I necessarily subscribe to all of what is being said, at least for the average road car which is what I work on. In any case, access to dynos is limited to most of us. I have seen video though of F1 engines being “run in” on a test bed. Much like Dr. Porsche, it’s birth by fire with full throttle surges up to 16 or 18,000 rpm and plenty of stirring on a sort of gearstick by the operator. The engines screamed and twisted violently on the test bed, and I could see the huge amounts of fuel being poured in the inlet trumpets. It’s a wonder the engines stay together! It’s not so long ago that revs of that order could only be attained by model aeroplane motors!
I’ve rebuilt lots of engines and this is my way of running in. I don’t thrash them, but neither do I baby them during the initial running in phase. I prime them well with oil and fuel before hitting the starter, and generally they fire up first or second attempt. After checking for leaks etc. it’s off out onto the road for running in. I don’t let them stand idling excessively before heading out, that’s a recipe for glazing of bores. I accelerate them moderately on the flat and on hills up to high mid revs (3,000 – 4000) in bursts, and then I let the speed drop back without braking. I’ll keep this going for at least 30 mins., driving the car in different ways, but extending the stress a bit more each time. The worst thing to do is to cruise along at the same speed without making the engine work.
The theory I subscribe to is that the engine must be made to work in order to bed in (mainly) the rings, but not be stressed so much as would build up excessive heat in the critical areas due to friction, and possibly damaging these components. That’s why the car is driven in bursts, to allow the engine to work and then to dissipate the heat generated by the new components rubbing together. A new engine will always produce more heat than a sloppy old worn out one, that’s why the cooling system must be 100% with a new engine.
As far as oils go for running in, the simpler the better. You don’t want the best slippery oil on the market, you want something rather basic that while it will lubricate, will permit some rubbing together of moving parts to allow them to bed in. Basic SAE30 (running in oil) does the job real well for 1,000 k’s. Then switch to a good quality NON friction modified multigrade oil. I have yet to be convinced that FM oils, in whatever guise they are sold (tungsten magnaxxxx etc) are any better than a good quality multigrade. More likely that they will cause problems by not allowing parts to bed in as they should. Remember all the problems with early Commodores (why am I not surprised) and a certain brand of FM oil that sponsors V. Bray! I won’t use them.
And, doing running in this way, I’ve never had a car (engine, that is) one come back with problems. That’s my 10 cent’s worth!