Switching to synthetic
Thread Starter
Heel & Toe
Joined: Oct 2021
Posts: 22
Likes: 10
Switching to synthetic
Hey Everyone. I bought my corvette with a crate engine already installed by the previous owner. The break-in instruction sheet that came with all the paperwork states that use of synthetic oil is not recommended until the engine has at least 6000 miles. I’ve been using conventional with zinc for the previous few changes but was going to switch to synthetic this next time. My question is, what is the reason for such a recommendation on a new motor? Thanks to anyone who can explain.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Seating of the piston rings. Synthetic may lubricate too well to insure good seating, depending on the ring face surface and the cylinder prep. OEM's can prep a cylinder much better than aftermarket and use moly faced rings that seat almost immediately, so they do not require conventional oil for break in.
Although given the oil consumption problems that OEM's are experiencing and have been for over a decade, I believe they have moved too far in the direction of not needing a break in.
Although given the oil consumption problems that OEM's are experiencing and have been for over a decade, I believe they have moved too far in the direction of not needing a break in.
Safety Car
Joined: Jul 2005
Posts: 3,697
Likes: 833
From: WI
They probably figure two oil changes I'm guessing. W/o knowing how anyone is going to drive their particular car (engine), 6k probably covers most contingencies (by the rebuilder). I think there's a bit of SWAG when coming up with a number like that.
Melting Slicks
Joined: Feb 2007
Posts: 2,709
Likes: 269
From: S.E. MI
St. Jude Donor '15
I used the GM recommended break in procedure on my new crate engine.
https://www.crateenginedepot.com/pdf...gineDeluxe.pdf
https://www.crateenginedepot.com/pdf...gineDeluxe.pdf
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
It depends on how it's broken in. Personally I warm an engine up to full temp, make sure the timing is right, then accelerate hard and decelerate aggressively for a good 50 to 100 miles. Then change oil, still conventional drive it hard for the next while.
then next change at 3000 to synthetic.
then next change at 3000 to synthetic.
Last edited by REELAV8R; Nov 7, 2024 at 01:23 PM.
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Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
Team Owner
Joined: Jan 2007
Posts: 53,648
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From: Southern Cal Ca
St. Jude Donor '22
6k could be min for certain ring type spec.
I have seen 10-15k numbers.
Important to work rings both ways
1, under power to expand in downward direction
2, under decell/eng braking to expand upwards.
ex. low gear slowing from high speeds.
roller cam people forget ring seating.
I have seen 10-15k numbers.
Important to work rings both ways
1, under power to expand in downward direction
2, under decell/eng braking to expand upwards.
ex. low gear slowing from high speeds.
roller cam people forget ring seating.
Advanced
Joined: Sep 2012
Posts: 87
Likes: 25
From: San Diego CA
I have a 72 LT1 with flat tappet lifters/cam I see that they do not seem to be selling Valvoline 20 50 racing oil in my local auto parts stores anymore except for one quart at 10 bucks each. How would one keep the proper zinc with synthetic oil? Many thanks
Is my vette stock?? HAHA
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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Hey Everyone. I bought my corvette with a crate engine already installed by the previous owner. The break-in instruction sheet that came with all the paperwork states that use of synthetic oil is not recommended until the engine has at least 6000 miles. I’ve been using conventional with zinc for the previous few changes but was going to switch to synthetic this next time. My question is, what is the reason for such a recommendation on a new motor? Thanks to anyone who can explain.
Thread Starter
Heel & Toe
Joined: Oct 2021
Posts: 22
Likes: 10
Just wanted to get your name straight so when you are wondering why your cam is flat we can give you a good answer....does your crate motor come with a warranty? does it have a roller cam? Why dont you want to follow simple instructions? You can call the manufacturer for the answers
Pro
Joined: Feb 2017
Posts: 518
Likes: 365
From: San Diego
2023 C3 of the Year Finalist - Modified
I am with you and just curious too. Why do you want slippery to help the cam but not slippery for the rings? Seems to be conflicting objectives. There are probably a bazillion answers on the web but getting to the bottom of it can be exhausting. I'll listen on the sidelines if someone has a quick answer.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I am with you and just curious too. Why do you want slippery to help the cam but not slippery for the rings? Seems to be conflicting objectives. There are probably a bazillion answers on the web but getting to the bottom of it can be exhausting. I'll listen on the sidelines if someone has a quick answer.
Piston rings on the other hand HAVE to touch the cylinder wall and actually wear into that cylinderwall surface on a microscopic level. This is done to insure sealing of combustion gasses above the top ring and oil below the bottom ring. If this is not done properly you will end up with combustion gasses in the crankcase area and oil in the combustion area to an excess. Both of which cause problems with engine running. So in order to create the seal as best as we can we allow the ring as to "touch" the cylinder walls.
the cylinder, after it's been honed, has micro high spots that the rings wear into. Once these high spots are worn down it can't be redone unless disassembled and re- honed. If it's not allowed to wear in properly then you get a "glazed" cylinder wall that will not seal properly to the rings and you end up with the associated problems, oil consumption, reduced power, excessive blowby, carbon buildup, etc.
Pro
Joined: Feb 2017
Posts: 518
Likes: 365
From: San Diego
2023 C3 of the Year Finalist - Modified
Rings are not like bearings. Bearings ideally never touch metal to metal, there is always a film of oil between surfaces.
Piston rings on the other hand HAVE to touch the cylinder wall and actually wear into that cylinderwall surface on a microscopic level. This is done to insure sealing of combustion gasses above the top ring and oil below the bottom ring. If this is not done properly you will end up with combustion gasses in the crankcase area and oil in the combustion area to an excess. Both of which cause problems with engine running. So in order to create the seal as best as we can we allow the ring as to "touch" the cylinder walls.
the cylinder, after it's been honed, has micro high spots that the rings wear into. Once these high spots are worn down it can't be redone unless disassembled and re- honed. If it's not allowed to wear in properly then you get a "glazed" cylinder wall that will not seal properly to the rings and you end up with the associated problems, oil consumption, reduced power, excessive blowby, carbon buildup, etc.
Piston rings on the other hand HAVE to touch the cylinder wall and actually wear into that cylinderwall surface on a microscopic level. This is done to insure sealing of combustion gasses above the top ring and oil below the bottom ring. If this is not done properly you will end up with combustion gasses in the crankcase area and oil in the combustion area to an excess. Both of which cause problems with engine running. So in order to create the seal as best as we can we allow the ring as to "touch" the cylinder walls.
the cylinder, after it's been honed, has micro high spots that the rings wear into. Once these high spots are worn down it can't be redone unless disassembled and re- honed. If it's not allowed to wear in properly then you get a "glazed" cylinder wall that will not seal properly to the rings and you end up with the associated problems, oil consumption, reduced power, excessive blowby, carbon buildup, etc.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa