rebuilt 502 burning oil
 

my 502 was redone over the winter. it always burned oil and is still doing it. about a 1/2 quart every 1-2 hours. is this common? no leaks at all. i change it out every 10-15 hours. using napa premium 20-50 with wix racing filter as per my motor builder. also can you check it on the trailer or do you always check it in the water?. thanks mark

Sounds normal to me. Very dependent on how hard you run it. rebuilt stock?

Gm 502's originally used j/e pistons with metric low tension rings,it sounds like you re-used your pistons and the rings even though they may be new are not sealing. When my boat was new in 2000 it used oil like crazy,I made those pistons into ash trays and put in j/e srp's with STANDARD rings,it barely burn't 1 quart of oil every 10 hours after that even with a supercharger. The replacement pistons were a few thousandth's bigger so you could hone the block on a tq plate and re-assemble it without boring it out,they weighed so close it did not need re-balancing either. Smitty

Oil Usage
 

Just my 2 cents but ...I have seen a lot of engines rebuilt and
use abnormal amounts of engine oil....
On big blocks the finish of the cylinders is extremely important
if they are too rough you will go thru everything in the crankcase in a day!

WHY DON'T YOU USE 40WT OIL AND SEE IF THAT HELPS...

isn,t rebuilt stock. pushed it up to 550 hp. cam, heads, stainless marine exhaust. the motor only had 300 hours on it so we did reuse the stock pistons with a hone. new rings, new mains. i had heard that they are built to run a little wet. we also are running a 150 degree thermostat but i really don,t think thats the cause. i understand the 40 wt option but i am trying to keep with the program that the mechanic told me to follow. just trying to learn and get fresh ideas.

How good is NAPA oil? Sounds like the rings never seated. Maybe the hone was not correct for the ring you are running. I would also check you pcv system. Just a suggestion.

I UNDERSTAND EVERY MECH HAS HIS OWN OIL THEY USE BUT WHEN I DO A MOTOR I ONLY USE 40WT NEVER SEEM TO HAVE A PROBLEM (THAT WHAT MERC PUTS IN THE HP 500'S)BUT LIKE OTHERS SAY MAYBE THE RINGS DID NOT SEAT GOOD LUCK....

That seems like a lot of oil consumption to me. Really, on a fresh engine with a new bore/pistons/rings, I don't think you should see any real measurable loss of oil. My re-done 454 has around 20 hours on it and I have seen no oil loss at this point. The oil was changed at 8 hours after the first weekend on it, and I'm getting ready to change it again. I am running Amsoil 20W-50 and the Amsoil filter.

what brand of 40 wt are you using? are you checking it on the water or trailer? i really don,t want to run a synthetic. to expensive to change at 10-12 hour interviles. would my wix filter be holding alittle? thanks mark