i plan on rebuilding my engine this summer and want to use mobil one oil. can i break the engine in using mobil one or should i use a different oil when breaking it in, and then change to mobil one? does it matter which one to start with?

 

yeah it matters, don't use synthetic for break in oil. i use 30w pennzoil in all the engines i do. run it 30 minutes and change oil and filter again with 30w dino. than again at 3000 miles and switch to synthetic then.

 

I've heard that you shouldn't break in an engine on synthetic. I've also heard that that's old school thinking. I haven't seen proof either way.

what was the point of my reply??

 

I would like to know why you shouldnt break in on synthetic, other than the fact that it is a fair amount of money you are wasting to run the motor for 30 minutes.

Ben

 

You shouldnt try to break in an engine with synthetic because it wont break in. The synthetic oil is so good that your rings wont seat.

 

...which is somewhat confusing, since the factory reportedly breaks in new engines on synthetic. I wouldn't either, mainly since it is a collossal waste of money - especially with the moly contamination from a flat tappet cam break-in lube. All the bits, pieces, junk, debris, and polished off metal particles are going to land in the oil in a short time, so you want to change it fairly soon after starting the fresh engine.

Besides, a little friction on a fresh start can be a beautiful thing.

 

If you use a flat-tappet cam, DO NOT attempt to break it in with synthetic.

If you use a roller cam, then you can use synthetic for the initial fill, like the factory does these days.

Don't use moly for any of your build-up lube, then you won't have problems with it. I use white lithium on valve train parts, and either light engine oil or ATF on bearings. But no matter what you use, the first oil change should be after no more than 1000 miles, probably at 500 miles.

 

I read some were that Gm found a way to hone the block so it would seat the rings even with synthetic motor oil.
It did not give any details on the hone process, I guess GM is keeping that a secret.
Anybody have any ideas on how they do it?

 

Man, I must waste a lot of oil. My first oil changes are after about 4-5 hours, and usually it's prestty nasty right about then.

I've used the Comp- or Crane-supplied break in lube to maintain warranty, and the Crane stuff certainly appears to have moly in it.

 

well the reason i am asking is cuz my dad just rebuilt his 69' 383 roadrunner engine and dumped mobil one synthetic in it, but he hasnt started it yet. he asked me what you guys would have to say about it cuz i had no idea. but now i know and thanks for the responses. any other thoughts?

 

I doubt it will jepordize the overall durability of the motor. I played it safe though, dyno on inital run, dyno for the next two oil changes, and no WOT for 500 miles.

 

I always fill with some decent dino oil AND I also fill the cooling system with water. Puking water if you get leaks on a new engine isn't that bad.....puking anitfreeze sucks..here kitty kitty ...just kidding.


I don't worry so much about moly etc, because if it's a roller motor, I normally use STP oil treatment on bearings etc when assembling. It seems to stay in place better after install.


The thing I always worry about is all the gunk in the block from the machining process. And YES I do spend alot ( way too much ) time cleaning all passages with brushes, rinse repeat...


I normally fire it up, get the timing set, check for leaks and temp, then give it a short break in run. I follow the ring seating instructions that used to come with GM rings ( don't know if they still do ). Drive the car up through the gears ( not high RPM's ) and then do a couple of "coast down" runs, where you gas it, and then quickly let off the gas and let the speed come down.

After this run I change the oil to dino again. 500 miles later, if no leaks are present, go to Mobil 1 and be happy. BE SURE and change the filter both times.....if you don't believe there's alot of crap floating around in that rebuilt engine, cut the filter open after you take it off......

Of course, I'm also one of those that think that running full synthetic and changing it every 3000 miles is ***'s way of saying you have too much money and time on your hands. I normally go to 5000-7500 miles between changes, depending on driving conditions.

Must not be too bad on an engine. My wife's '96 GP 3.1 has 124k miles on it, and it gets Mobil one DINO oil. And I am SLACK about changing the oil. Every 5000-8000 miles at best. Car still gets 28 mpg with the original platinum plugs and wires

Did I mention it's paid off now?

Never had a problem yet with doing this on every engine I've built and installed. Except for the "zero gap" rings that had massive blow bye......but that's another story.


HTH

 

You can use synthetic if you want to do what my dad did on his 55 chevy way back when, to get the rings to seat GM recommended sucking in some Bon Ami cleanser at the carb. Just kidding but he really did it.

 

the rings seating isn't so much a problem as the cam and lifters break in, but the rings are still a concern. if you use a roller cam synthetic should work, but still i'd use dino.

 

I've used synthetic in the last few roller cam motors I've built.... works fine. Flat tappet cams however will not break in properly: there has to be enough friction between the cam and the lifter to force the lifter to rotate in its bore; if it doesn't start to rotate right away at intial starup, the lobes are not long for the world; synthetic lubes them too well, and they slide on the cam and fail to rotate and wipe out as a result.

It has nothing to do with the rings. That's an "old wives' tale" about like the one where you have to run non-detergent oil to seat the rings. May have been true with Model T motors, but it isn't the case today.

 

i usually run it on regular oil first.... run for 20 or 30 mins then change it.... then change it at 500 to regular..... then at 3000 start using synthetic blend and stick with that..... but those were on the hyd. flat tappet motors ive helped build. Never touched a roller block in my day.