General LSX Automobile Discussion - Why is it bad to run Synthetic in a brand new engine?

Could someone give me a valid reason why you want to run regular oil and not synthetic?

In a brand new motor there can be contaminants in the case and what not plus synthetic is not as viscous as conventional. In a brand new motor you will be typically changing the oil before 3K miles so it's not worth the cost of the first 2 or 3 oil changes. But to be honest with you I don't think it will harm your motor, just another one of those myths. Farrari's Lambo's and vettes all come with synthetic brand new.

I've always heard to put off running synthetic for 6-8k because the synthetic oil would increase the time the engine requires to properly break in.

But as Chris said, many exotic european cars and Vettes leave the factory with Mobil 1 already in them.

Re'

Actually, using synthetic oil may prevent the engine from breaking in properly at all. A new engine needs to wear itself to the point where the rings and and pistons seal themselves as well as they can to the block and promote higher compression-this may not happen if synthetic oil is used, because synthetic oil is extremely viscious and prevents that wear from happening.

Of course, one has to ask why 'Vettes were shipped from the factory with synthetic in their crankcases?

Actually, using synthetic oil may prevent the engine from breaking in properly at all.......

Of course, one has to ask why 'Vettes were shipped from the factory with synthetic in their crankcases?

This is exactly the proof as to why running synthetic in a new LS1 will not harm anything. If it did, then all the Vettes would have internal issues not seen in the F-bodies.

Not to mention, synthetic has been the factory fill for Corvettes going back to the LT1 in 1992.

ive heard of it keeping an engine from breaking in though both my SS and GTO came with syn.


im considering on my next new car to change my oil at 25 miles with non syn. to help it break in faster.

In the case of the vettes and now other GM cars/trucks, I'm sure GM has built the motor differently. As stated above you need to let the engine break in alittle.

I think the only issue was seating the rings. Depending one the rings used and the wall finish synthetic oil might not allow enough wear. If the right combination is used then synthetic can be used right off the bat.

I think the only issue was seating the rings. Depending one the rings used and the wall finish synthetic oil might not allow enough wear. If the right combination is used then synthetic can be used right off the bat.

You pretty much hit it ont he head..also the machine work and hone is specialized at the factory to allow a synthetic break in. Its hit or miss and joe blow's engine shop down the street.....thats why the regular oil theory persists....wit good reason...nobody likes rings seating shitty...

Thanks guys. Reason i asked was because i wanted to add RP fluids to everything in the C6 but duh i totally forgot it comes with M1 synthetic from the factory.

i bought my ss with 13k miles on it, but the previouse owner has all paper work even every oil change sheet and stuff he changed it in 2000 after 1500 miles and put synthetic in it

The new 'vettes come with synthetic from the factory because the Mobil pays GM major bank to use the endorsements in marketing. Plus they probably give them the oil for free. There are no other reasons. If you think it's to protect the engine better, in the words of Homer Simpson "...you're living in a dream world."

Any decent oil, changed when the light comes on will take these engines well over 100k miles if no other major factors occur like overheating, running in dust storms with a leaky intake, etc.

I change the factory oil out at 500 miles with a very good dino oil (Castrol GTX). I run GTX until the engine stops consuming oil. Usually around 5-7k. Then a good synthetic goes in.

A few years back, some new LS1s had oil consumption problems that were attributable to the rings not seating due to synthetic oil. I believe the 'vette even had a factory
TSB out on it.

I think the only issue was seating the rings. Depending one the rings used and the wall finish synthetic oil might not allow enough wear.

bingo. supposedly synthetic doesn't allow the friction needed for the rings to wear into the cylinder properly. myth or not there's no harm in starting off with dino oil after a rebuild.

dino oil is always safer...but I think with the correct production technique....and break in procedure(ps I totally disagree with factory procedures..I like the dynotune one) I think syn is ok in a FACTORY motor..anything I build gets run on dino oil until 500 miles...and then....syn and beat it like there is no tomorrow

if your talking about a rebuild engine then it wouldn't be worth it for the break in. if your talking about a new car from the factory they are pretty much broken in. most engines have around 20 hours of being tested before they are placed in a vehicle.

lt1 and ls1 vettes has to have synthetic motor oil from the factory and they dont have problems