388 SOLid RoLLeR

Im going to use Mobil right from break in on my new 388 when its done. Why? because Mobil has killed the issue themselves. If you want your motor to be protected from day 1, use mobil :yesnod: :yesnod:

is the cost of 1 oil change worth a new motor? :nono:

Matt383

The issue is your new rings will take forever to seat properly...if ever.

crheinish

Yes it's ok for break in. If you have questions call them at 1-800-662-4525.

388 SOLid RoLLeR

if the rings didnt seat, GM or POrsche or whoever wouldnt use them in brand new cars. And yeah..call that number :yesnod: :cheers:

lead_foot

Here's a quote from Comp Cam's Installation instructions, step 5 "We do not recommend the use of synthetic oils with our cam and lifter packages during break-in." For what it's worth. :)

Matt383

My experience is that brand new cars/motors are different than hi-perf rebuilds. The rings/pistons, heck all the parts, usually,.... or should be... better than the manufacturer's. I'm sure my C4 didn't do 10 second quarter miles right from Bowling Green! Any way, in a hi-perf rebuild, the tolerances are tighter and materials are different. I am NOT comparing breaking in a new car VS. a rebuild. That is not the point, unless I missed the original question of this thread which was breaking in a rebuild.

SPD DMN

I use the house brand of 30 weight to break in my motors, whatever is in stock that is straight 30 weight. Especially for the first 20 minute break in as all you want it to do is suck up and assembly lube and small fragments.

Not sure why people insist on even thinking of breaking in a motor on sythetic. Are you afraid of getting deposit build up in a motor in 500-100 miles. THE RINGS WILL NOT SEAT PROPERLY IF YOU USE SYNTHETIC. If you think you are doing yourself a favor by running it for break-in, think twice because you are not.

Robey, you are thinking about it too much. ;)

Chris

Dan Parker '96

Alright... here's the dope.

Ring composition (ductile iron, chrome, moly faced, etc.), the hone finish, and the engines design factors (rpm, piston speed, cylinder size, etc.) are deciding factors on "ring seating".

When thinking about cylinder break-in... forget about rings (as long as they are matched to the finish) and concentrate on the cylinder bore finish itself. The primary job of a proper hone finish is to ultimately be able to hold just enough oil so the rings do not contact the cylinder wall while being able to contain cylinder pressure.

On a freshly honed cylinder (even one that's been finished properly with a plateaued surface with the proper cross hatch) there are still peaks of material that need to be "ground down" so the bore finish ends up totally smooth with enough remaining grooves to retain just a pinch of oil to prevent said ring to cylinder bore surface contact. That's what happens during "break in". You are actually conditioning the cylinder bore and not the rings. Modern factory engines are usually "broken in" (cylinder wise) within 20 minutes of run time.

Now, on a much smaller level, the only thing that will prevent the rings from scraping off these peaks on the cylinder wall (with a fresh hone) would be an excessively viscous oil and/or a mismatch of ring material to hone finish. As for oil, it would have to be powerful enough to compress the ring as it travels over a cylinder bore peak and therefore not allow the ring to shear it off. As long as you use the recommended viscosity oil it will not make a difference if it is synthetic or not.

There are many variables involved with cylinder hone finishing. There are certain grades of finish and cross hatch angles that are matched to the type of ring used and the application of the engine. I don't have my links handy but will dig 'em up and post them soon.

But the bottom line is... dino or synthetic... it doesn't matter.

Robey5

Now I think that we are getting somewhere. One point that I may add is that I did not have the rings and wall hone "matched." I got some hastings rings (not from the dealership) and had the machinest run a cylinder wall hone at the normal stock (I believe it is) 37 degrees. Anyhow, the Chiltons manual will be looked into this evening, and I will call the number. The GM service manual does not say anything about oil to use.

I talked to the machinest yesterday, he reccommended 0w30 or 5w30 for the first 3-500 miles. Then switch to synthetic. So does this meen that I have to to an "engine flush" prior to the switch???

BTW, I finished the exhaust last night. I am 95% done, next I have to put the interior back together. :)

Robey5

Now I think that we are getting somewhere. One point that I may add is that I did not have the rings and wall hone "matched." I got some hastings rings (not from the dealership) and had the machinist run a cylinder wall hone at the normal stock (I believe it is) 37 degrees. Anyhow, the Chiltons manual will be looked into this evening, and I will call the number. The GM service manual does not say anything about oil to use.

I talked to the machinist yesterday, he recommended 0w30 or 5w30 for the first 3-500 miles. Then switch to synthetic. So does this mean that I have to do an "engine flush" prior to the switch???

BTW, I finished the exhaust last night. I am 95% done, next I have to put the interior back together. :)

Matt383

Wow!
You gotta love this forum! Ive been having this debate for years with builders, shops, etc. and still nobody agrees on this issue of syn vs. dino for break-in. I've heard from/talked to nationally known engine builders, "hi-perf specialists" ( who I cannot mention due to the fact that they own shops that are not sponsors here and I don't want to break the forum rules) who are divided on this issue. So I guess you go with what you think is best from the people you trust 'cause it looks like it's not going to be "solved" here. We've heard from very knowledgeable sources advocating both sides of this aurguement. So I know what I would do, yet I know that there are some members that will have an opposing point of view and that's great.
RE: The flush.... Just change your oil, forget the flush, you'll do more harm than good on a new engine and I'm not about to go into the chemical explaination of this either. Just my opinion... and I'm sure there is someone else that will disagree. Good luck! :cheers:

needanother1

You shouldn't have to flush it before switching to the synthetic. Personally I'd do the initial oil change at 300-500 miles, put the same kind of oil back in and run it for another 500 or so, THEN switch to synthetic. Not because of the synthetic vs. dino issue, but just because I believe in the benefits a couple of oil changes in rapid succession on a rebuild. And I, personally, hate to dump out $30 worth of Mobil 1 with 500 miles on it.

Good luck with your car!

Jason

Matt383

:iagree:
:yesnod:

88_vette

For starters, I agree if you are going to change the oil several times within the first 1000 miles. Then there is no need to use mobil1. It will not effect your breakin. Just save money if you are worried about money.

2: Syn. oil does not effect the rings sealing. Lets think about that for a second. What you are saying is the oil is so great at cutting wear it will not let it happen for the most part. Well, if the wear is reduced so much then how do the rest of the engine parts breakin. There is no special honing on the crank, rockers, or cam. If it cuts wear enough to not allow breakin of the rings, then it would have the same effect on the rest of the metal to metal parts. You can't pick and choose which parts it protects better. With that said, call the 1-800# on the back of the mobil1 bottle. After all you paid the big money for the oil use it. Call them and ask them. I did. They said that yes the oil does reduce wear a great deal compared to dino oil, but not enough to effect breakin. There is more to syn oil than just wear protection.

FD2BLK

I just had to know so I did call the number and they said quote on a rebuid it is better to run convetional motor oil for the first 3000 mile and then you can switch to synthetic to ensure proper break in and that is from molble 1 tech line, Not only did this confirm what I have always been told by every machinist I have ever used and Comp Cams(I called them also) it also confirmed my gut feeling BTW I called at 11:30am

Matt383

Now it's settled! :iagree:
Right from the horses mouth, er, tech line.
Thanks ejfagala! :thumbs: :thumbs: :thumbs:

yoslambo1@cs.com

DO NOT USE MOBILE 1 FOR BREAKIN!!! :eek: you should use straight 30 oil. i use valvoline sae 30 ! :yesnod: if you try to break in the engine with synthetic your rings will not seat! :eek:

rockken_vette

I know - fill it half dino, half synthetic! :D

Robey5

Well, that is the most logical thing that I have heard... :p:

I guess that I will do an oil change. I (currently) have a pan full of mobil 1. I am going to break her in on dino, for the first 1000 miles or so, and do an oil change at 500 miles. That is my end solution, unless someone can tell me to do differently.