Hey everyone I just finished rebuilding my brothers engine...he has a 2.8L V6 in his 87 Firebird...we had the cyl walls honed...so new piston rings were installed...we stuck with the originall cam ( i think the guy who owned it before us put a new one in there) cause it still looked brand new. new main bearings, connecting rod bearings..new cam bearings, all new gaskets, new distributor and oil pump....i think thats pretty much sums it up....so...

How do we breakin the engine...what kind of oil do we use? I was told to break in a new cam you use non detergent(sp) oil...non-synthetic...but we are useing the old cam...so i went a ahead and put in 5W-30 synthetic oil....but now i JUST read something that says not to use synthetic oil at first cause it will glaze they piston rings (disclamer...this info was on a motorcyle web site...but i figure...an engine is an engine) What kind of oil should i use...i just finished the rebuild yesterday and it us up and running today. Thanks for any info/help.

-Mike

 

you'll get a lot of differant answers on this one. what i like to do is fill it with 30w oil start it and set timing look for leaks. let it run for around 30 minutes, to operating temp, between 1000 and 2000 rpm varying the load ocasionally. shut it down drain oil, refill with 30w and repete, except for the oil change. after it's cooled restart and drive easily to moderately, no full throttle driving for a few more hours or 500 miles then change oil and drive to next regular oil change then drive it any way i want.

 

hey thanks....well last night we let it run at idle with the synthetic 5W-30 oil in it untill it got hot...then to see how it ran under load we drove it around the block...everything ran great.

So now that it has been warmed up and it run for about 30 min max...you think i should change the oil again? this time do you think i should stick with the non synthetic 30W?....then after 500 miles change the oil to 5W-30 and call it good? thanks for the reply

-Mike

 

from what i hear you should never run a rebuilt engine with synthetic, but lot of people have. i like to change the oil after 30 minutes because of all the assembly lube that gets into the oil.

 

A flat-tappet cam should not be run in with synthetic oil. But, if yours is roller (I don't know if it is or isn't), and/or you re-used the cam & lifters, it shouldn't be a problem.

With new rings, a very slight wear needs to occur between the cylinder wall and rings to "seat" them - i.e., so they fit well together. The "problem" with using synthetic is that wear is reduced, so it can take longer for the rings to seat. Increased blow-by and oil consumption can occur until the seating occurs.

Like ede, I change the oil & filter after the initial run-in to get rid of the rebuild debris. I then usually put 500-1000 miles on the engine with non-synthetic without running it hard, and if oil consumption is acceptable (i.e., low), then I'll switch it over to synthetic and live happily ever after.