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I heard that you aren't supposed to use sythetic oil for break-in oil right after a re-build because it doesn't give the piston rings a chance to bite into the cylinders. And thereafter the motor will always use oil. Is this true? If so what type of oil should I use for the break-in? I plan on using Mobile1 synthetic for regular use.

Thanks,
C.Wade
 

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Depends on what oil consumption you can live with.

Porsche factory fills with Mobil-1 and just says the engine will consume XQts per 3000 miles.
"Break it in" is also a relative term. What do you do? Run the engine until you see cylinder leakdown tests stabilize in the 3-5% range and then switch from Dino Oil to synthetic. With out actually checking the leakdown, you may NOT be getting the rings "Broken in" and though your oil consumption may be lower, your rings blowing by will not be optimal.
It's a loaded question, and I'd dun Dino oil in Straight 30WT until leakdown stabilizes, then flush it all out and go with synthetic...

But I don't use synthetic in street cars' engines myself. Only tranny and Gearbox...
 

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Re: Depends on what oil consumption you can live w

I have always used straight 30w non detergent , dyno oil. usually run for 500 miles with it , making sure not to rev the motor out too bad. of course this is one of those questions you are goin to get 10 different ways of breaking an engine in .......

~Kenny
 

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Re: Depends on what oil consumption you can live w

You should run a quality mineral oil (I strongly recommend Castrol 10W30) until your first oil change at around 700miles. This will help the rings seat as mentioned. I have had numerous engines rebuilt and this is a procedure that has worked for me and strongly recommended by engine rebuilders. The key to breaking in an engine is to give it a varying load through the rev-range but at the same time you do not want to take it above 4,500rpm. So a mix of city driving and highway driving will help, taking the car for a 1000mile trip on the highway while the engine just sits at 2,500rpm all day will do it no good.

For the tranny and diff I always use Amsoil synthetic, but on all my engines I run regular Castrol GTX 10W30 in the winter and 20W50 in summer and I do oil\filter changes very frequently. After all its only $10 and cheap insurance for engine longevity.

Good luck - Yasin
 

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Re: Depends on what oil consumption you can live w

single weight. 30W is best choice. Basically, you want the purest oil you can get with no detergent or additive
 
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