how many miles break in, before switching to synthetic motor oil ?

[Blue Grey Duster]

I have a motor with about 250 miles on it, and it has been sitting for 3 years. I wasn't thinking about the rings and I put synthetic oil in it, and after 25 miles, the oil is dark. I figure it's blow-by.

I'd rather run synthetic, but it looks like the rings aren't seated and I'll have to go back to regular oil. I will be mostly racing this motor.

Any experience here, would be greatly appreciated.

 

[1970Duster]

On a street motor a 1000 miles will usually do (up to 1500 miles if your using gapless piston rings), so if it is a race motor and see much high Rpms then perhaps 750 miles

 

[JTG]

The bottle of Red Line synthetic oil I'm holding as I type this, recommends after the first 3000 miles to start using it, if its a freshly rebuilt motor. Hopefully upon the first initial start up you used breakin oil inconjuction with regular oil.

 

[Blue Grey Duster]

Thanks for the good info. guys ! I guess I'll try the switch again, a little later down the road. You Guys make this site the Best. :walk:

 

[moper]

Yeah, depends on the rings, but chances are, you did it a little too early. I say 100 miles, and my rings are seated almost fully within minutes. Waiting gets the first early oil change done so there's not so much moly and crap still coming off the parts with the good oil in it.

Edit.. That was supposed to be 1000 miles... lol. Sorry.... cant believe I missed that.

 

[Beatnik]

Flat-Tappet cam? Never...no need. If you feel you have to use a synthetic, then add a bottle of ZDDP additive to each oil change