Which Oil for break in??
Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
Hope the break in goes well.
Eric D
Le Mans Master
Joined: Sep 2007
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From: Belleville Il
Unless the builder specifies something else and then only for warranty purposes,,otherwise go with M1. I think I'd do 500 on the first fill,,oil and filter and good to go IMO!!
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,737
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From: California USA
I think some don't realize FORGED pistons have different wall clearances. Engine shop mentioned that
the synthetic was too slick for good break in because of this. They put VR valvoline in for 15 min, then changed it
again. Now I've got about 800 or so miles. Engine has used about 1 qt. It must be sealing though as it has over 500rwhp. In case I didn't mention JE FORGED PISTONS and LS2 BLOCK.
You are the 2nd person I've talked to that mentioned 20-50 Rotella.
I wonder if there is any reason to use regular Synthetic w/this setup?
I do plan to after break in.
Last edited by 427CPE; Aug 14, 2008 at 01:35 AM.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,737
Likes: 2
From: California USA
That whay my instict tells me, Synthetic. I'm a fan of the Amsoil brand, but engine builder said its too slick for the break in.Just trying to get a few ideas early on w/the break in.
Safety Car
Joined: Jul 2004
Posts: 3,904
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From: Vancouver Washington
The new book How to Rebuild GM LS-Series Engines strongly recommends against using any synthetic oils for the first few oil changes. They claim the use of synthetics during break in won't allow the cylinder walls to properly seal with the rings. They even refer to the fact that GM and other OEMs use a factory fill of synthetics and that rebuilds won't have the same cylinder wall finishes and need non-synthetics for break in.
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Safety Car
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From: panama city beach florida USA
St. Jude Donor '09
The new book How to Rebuild GM LS-Series Engines strongly recommends against using any synthetic oils for the first few oil changes. They claim the use of synthetics during break in won't allow the cylinder walls to properly seal with the rings. They even refer to the fact that GM and other OEMs use a factory fill of synthetics and that rebuilds won't have the same cylinder wall finishes and need non-synthetics for break in.
Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
The claim that the engine will not break in properly with synthetic oil is complete and total 
. It is VERY old school thinking and has NOTHING to due with ring to cylinder break in. Any rebuilder that is using a cylinder bore wall finish courser then the OEMs won’t be touching my engine.
On your forged pistons, LS7 and LS9 have them and use Mobil 1 for break in. In fact, if your bores are sized properly for forged pistons, typical they are a looser fit then cast pistons. This is due to greater thermal growth on the forge compared to cast.
Bottom-line, will it hurt a new engine to break it in on non-synthetic oil, most likely not, but to suggest that using synthetic is a bad idea is simply WRONG. It’s your engine and do what you feel is best. But in my opinion, if I just spent a gob of money in rebuild and upgrades, I want the most protection I can get and I would use nothing but what the factory uses, Mobil 1.
Eric D
. It is VERY old school thinking and has NOTHING to due with ring to cylinder break in. Any rebuilder that is using a cylinder bore wall finish courser then the OEMs won’t be touching my engine.On your forged pistons, LS7 and LS9 have them and use Mobil 1 for break in. In fact, if your bores are sized properly for forged pistons, typical they are a looser fit then cast pistons. This is due to greater thermal growth on the forge compared to cast.
Bottom-line, will it hurt a new engine to break it in on non-synthetic oil, most likely not, but to suggest that using synthetic is a bad idea is simply WRONG. It’s your engine and do what you feel is best. But in my opinion, if I just spent a gob of money in rebuild and upgrades, I want the most protection I can get and I would use nothing but what the factory uses, Mobil 1.
Eric D
Le Mans Master
Joined: Sep 2007
Posts: 7,604
Likes: 8
From: Belleville Il
The claim that the engine will not break in properly with synthetic oil is complete and total . It is VERY old school thinking and has NOTHING to due with ring to cylinder break in. Any rebuilder that is using a cylinder bore wall finish courser then the OEMs won’t be touching my engine.
On your forged pistons, LS7 and LS9 have them and use Mobil 1 for break in. In fact, if your bores are sized properly for forged pistons, typical they are a looser fit then cast pistons. This is due to greater thermal growth on the forge compared to cast.
Bottom-line, will it hurt a new engine to break it in on non-synthetic oil, most likely not, but to suggest that using synthetic is a bad idea is simply WRONG. It’s your engine and do what you feel is best. But in my opinion, if I just spent a gob of money in rebuild and upgrades, I want the most protection I can get and I would use nothing but what the factory uses, Mobil 1.
Eric D
. It is VERY old school thinking and has NOTHING to due with ring to cylinder break in. Any rebuilder that is using a cylinder bore wall finish courser then the OEMs won’t be touching my engine.On your forged pistons, LS7 and LS9 have them and use Mobil 1 for break in. In fact, if your bores are sized properly for forged pistons, typical they are a looser fit then cast pistons. This is due to greater thermal growth on the forge compared to cast.
Bottom-line, will it hurt a new engine to break it in on non-synthetic oil, most likely not, but to suggest that using synthetic is a bad idea is simply WRONG. It’s your engine and do what you feel is best. But in my opinion, if I just spent a gob of money in rebuild and upgrades, I want the most protection I can get and I would use nothing but what the factory uses, Mobil 1.
Eric D
That's my line of thinking for modern "roller" motors. You only really need Rotella on motors like my old BB shark with a flat tappet cam/lifters. I have to keep some of the old dyno oil in it,,and I still add some synthetic to it!!
Burning Brakes
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From: Nouvelle Ecosse
JC
Race Director
Joined: Dec 2004
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From: Haymarket VA
GM uses rings of a different material than the much harder rings used on your forged pistons. It has little to do with the wall finish. You run a very good chance of creating a lifetime oil burner trying to seat these harder rings using synthetic oil.
I run Rotella for 2 oil changes. First change at 1 hour and second change at 500 miles. I then run Valvoline NFS Racing oil for another 2500 miles. Both of these oils contain ZDDP which is an anti-scuff agent that the EPA made the oil companies take out of car oil several years ago.
After 2500 or even 5000 miles, then switch to synthetic.
My $.02
I run Rotella for 2 oil changes. First change at 1 hour and second change at 500 miles. I then run Valvoline NFS Racing oil for another 2500 miles. Both of these oils contain ZDDP which is an anti-scuff agent that the EPA made the oil companies take out of car oil several years ago.
After 2500 or even 5000 miles, then switch to synthetic.
My $.02
Tech Contributor
Joined: May 2008
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From: Howell Michigan
St. Jude Donor '09-'10-'11
Eric D
Le Mans Master
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From: In the pit, trying to love someone.
I ran Rotella 15W40 for the first 1000 miles. I then switched to Redline Synthetic. And you know what the Redline says on the bottle?
"WARNING - NOT FOR ENGINE BREAK IN."
The oil manufacturer THEMSELVES said do not use it for break in. That right there is good enough for me.
"WARNING - NOT FOR ENGINE BREAK IN."
The oil manufacturer THEMSELVES said do not use it for break in. That right there is good enough for me.
Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
I ran Rotella 15W40 for the first 1000 miles. I then switched to Redline Synthetic. And you know what the Redline says on the bottle?
"WARNING - NOT FOR ENGINE BREAK IN."
The oil manufacturer THEMSELVES said do not use it for break in. That right there is good enough for me.
"WARNING - NOT FOR ENGINE BREAK IN."
The oil manufacturer THEMSELVES said do not use it for break in. That right there is good enough for me.
Eric D
Le Mans Master
Joined: Jun 2002
Posts: 8,352
Likes: 103
From: In the pit, trying to love someone.
I'm just throwing it out there that a manufacturer of a synthetic oil is flat out telling you NOT to use their product to break their engine in. Aside from the Zinc and Moly content, how different is Redline from Mobil 1?
Race Director
Joined: Dec 2004
Posts: 13,760
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From: Haymarket VA
The final surface finish is to assist in seating the rings. Try throwing a new set of rings in an older engine without a surface hone and they will NEVER seat.
Safety Car
Joined: Sep 2003
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From: Cape Coral FL
Lingenfelter 403, Mahle pistons, Compstar rods, Callies crank, Clevite Tri Armor mains, Clevite cam bearings here. I ran Rotella 15W-40 diesel and Comp Cams break-in additive for the first 70 miles, driving it like I stole it. Then a change to fresh Rotella 15W-40 diesel and Comp Cams break-in additive for the next 500 miles. Then RedLine 10w-40 since. Have put about 1200 miles total on the car and no measurable oil usage in the last 700 with Redline.
The bearing clearances on a built motor are typically larger because it will allow more oil to run in between the bearing surface and crank. This is because the motors are pushed harder and the extra clearances help keep the bearing surfaces from binding. Yes a non-synthetic should be used for break-in as the cross hatch is typically a bit coarser on an aftermarket prepped block than an oem one. What seats and ultimatley 'burnishes' the rings for a good seal are the pressures in the cylinder while running. I took the advice of a very well rspected engine builder. You only get about 25-50 miles of good crosshatch to seat with, so you best get the best seal possible in that time. Otherwise you may have to tear it down and rehone it. Here is a good read on the subject: Break in theory.
The bearing clearances on a built motor are typically larger because it will allow more oil to run in between the bearing surface and crank. This is because the motors are pushed harder and the extra clearances help keep the bearing surfaces from binding. Yes a non-synthetic should be used for break-in as the cross hatch is typically a bit coarser on an aftermarket prepped block than an oem one. What seats and ultimatley 'burnishes' the rings for a good seal are the pressures in the cylinder while running. I took the advice of a very well rspected engine builder. You only get about 25-50 miles of good crosshatch to seat with, so you best get the best seal possible in that time. Otherwise you may have to tear it down and rehone it. Here is a good read on the subject: Break in theory.