496 mag oil consumption??
 

Hi all..I'm new to this site. I have a question...
What would be considered normal consumption of oil on a 496 mag?? The engine is an 05 and has 96 hrs on it. Ever since new the engine has used oil( which I thought and was told was normal)... but....since Labour Day, I've had to add 1 quart of oil after 6 hours of somewhat hard running. The engine runs very strong and has never given me any other problems..just uses oil. I see no leaks around the engine and I get a moderate amount of soot on the back of the boat...nothing crazy. The engine has never been on the rev. limiter.
The engine is in a Baja 25 Outlaw. I change the oil every 35 hrs or so and only use the Mercury 25 40w oil.
I would greatly appreciate any feedback you guys could give on what should be my next course of action..if any.
Thanks
Kyle M.

Re: 496 mag oil consumption??
 

sounds like a lot to me... i would wonder if its running rich which will do a couple of things.... fuel dilute the oil and make it thin enough to diasappear and make the rings lose their seal.... which, considering your oil change interval you just might not be noticing... if efi i might want to look at the sensor array and make sure its getting hot enough water temp... if carb... could be 100 things ... and if efi will be hard to see on the plugs because the ignition is so good... if carb i would expect to see the porcelin white/brown but the steel ring sooty.... doesn't take much to do what you suggest and the motor will still seemingly run well... just be a little lazy down low.

Re: 496 mag oil consumption??
 

Twin-Kyle:

496's sometimes use a little oil when new in break-in time 10-20 hours. At 96 hours this should be over with and even running hard at lets say 4500 rpms you should not be using quite that much oil. Make sure you are checking the oil with the engine level and not overfilling. The 496 pan uses exactly 10 quarts in the pan plus about 1/2 quart in the motor recesses and filter cooler system. If you still under warranty you will want to take it to a Merc dealer and have them right up the ticket for heavy or excessive oil comsumption. They should do a compression test and leak down test and verify all the cylinders are at spec. on compression and leak down rates.
A few 496's even new have sometimes developed piston and ring issues but its the exception, not the rule. Hope yours is something simple or its under warranty if not.

Ray @ Raylar

Re: 496 mag oil consumption??
 

they use oil in the trucks also, 1quart every 3thousand miles

Re: 496 mag oil consumption??
 

sure.. but thats the same as about 40 hours... give or take...and is essentially normal.

Re: 496 mag oil consumption??
 

Thanks for the advice...Thankfully the engine is still under warranty until next June. The Merc. mechanic and the manual says the engine holds 8.5 Liters of oil(which is about 10 quarts I believe) so when I do my oil change, that is what I put in. I will then run the boat then check the oil again, topping it off if needed. I have top it off several times since my last change so I thought it should be full by now.
On the last run out..I ran 50 miles..averaged 4000 rpm with some wot blast, engine ran for 3.5 hours. Upon my return, checked the oil...down 3/4 of a liter.
:eek: One Time last summer, I failed to check the oil for about 15 hours after the 20 check(under the assumption everything should be OK) When I did check, the oil was down so far it didn't even show on the stick!!(No alarm went off) I have kept a VERY close eye on it ever since.

Re: 496 mag oil consumption??
 

i had a ford f 350 that did that with 20,000 miles on it.... one piston had the rings installed upside down from the factory....

Re: 496 mag oil consumption??
 

My wife works at that factory that builds those engines. She said the rings can't be installed upside down, but...they can be installed in the wrong order. Something like that happens in the repair bay and not on the line. On the line, all the rings are installed by a machine. Pistons are installed by hand.

Re: 496 mag oil consumption??
 

Just for comparison, I experience virtually no oil consumption in a twin 496HO setup with 200 hours :cool:

Re: 496 mag oil consumption??
 

Same here, I have 225 hrs on my twins and Never had to add oil between oil changes. (every season or 100 hrs)
Sure it read a little lower than full when it came time to change, but never reached the add line.