Plum_Crazy

My wife was getting frustrated with high-perf boating when my last boat went through 3 engines in 5 seasons. I absolutely love the reliability of my twin 496HO's. We've had 3 seasons of trouble-free boating and these engines are now up to 420 hours and running strong. Plus, the wife now wants to go boating!

A.O. Razor

Our 496's in the cruiser has 780 hours on them. Not missing a beat. If you take care of them they'll take care of you. They are not build for tuning ect. but run as stock motors, just brilliant.

Dave M

I had a 2004 496HO w/ around 250 hours when I sold it. It didn't use oil. I had to replace the map sensor and IAC while I owned it.

GO4BROKE

iTrader: (1)

2002 496ho's, 620+ hours. Replaced seawater pumps and 1 IAC. Love them. I want to go boating, not wrenching.

Rookie

iTrader: (4)

I have no experience with a marine 8.1 496. I have heard nothing but good things about a stock marine 496. My friend had a 496 in his 2004 HD.Great engine for towing, always ran flawlessly but that thing would use more gas and oil than my 180HP 2stroke snowmobile. It was ridiculous.

Ray, do you have any idea why the big discrepancy between the 2 in those aspects?

Raylar

Three reasons some of the 8.1L's use oil in the trucks and not as much in the boat uses.
1. 2000-2004 model 496's-8.1L engines had some cheezy-too thin plastic intake manifold gaskets and too short intake bolts (silver in color) versus (black ) for replaced (GM Re-call) and later models.
The truck engine intakes when heated to 200 degree or so on the road temperatures would start sucking oil up from the lifter galley past the thin gasket into the intake ports and burn it off in the engine.
Anywhere between 1 quart every 300-1500 miles or so very common in early model trucks.
2. The truck engines where GM recommended to use mostly 5-30W synthetic oil, I believe the engine with its big bore and long stroke does not like these weight oils especially in slippery synthetic and some of this oil gets past the rings. I have talked to many 8.1L truck owners who switched over to 15-40w synthetic and the problem disappeared.
Remember in the boat engines the 8.1L 496 are recommended to run 20-50W or 25-40W blended or synthetic oils.
3. The early 8.1L 496 engines had pressed pins in the piston/rod setup and the piston had a pretty good offset in its pin placement and this would cause some piston thrust and resulting piston slap that was easy to hear in cold truck use. This thrust (slap) can cause the ring pack to pass some more oil and when using the very light weight synthetics in the trucks the oil pass problem was increased. GM actually paid to replace thousands of these engines in the early trucks to eliminate customer complaints and possible class actions.
In 2004 GM changed the piston and rod design and went to a full float pin and piston with less offset and the slap and oil burn problem was nearly eliminated.
In the boats with louder exhaust you could not really hear the piston slap noise and it disaapeared after the engine warmed in both cases. In the early engine boats again the heavier oil weights seemed to also eliminate the oil burn.

Forgot to mention that in any case or use a 496 -8.1L engine with a piston or ring mechanical issue will use more oil like any 4 cycle engine.

Best Regards,
Ray @ Raylar

682gold

iTrader: (3)

ok yall have convinced me that they are good engines thanks for the help

techman

Would running the 15w-40 be too thick for the NE climates?

blownhammer2000

iTrader: (1)

i've always ran 25-40 with no issues, though i am further south than you

Raylar

Since its pretty rare for any performance boaters to be out boating in the Northeast when the temps are really low I would not recommend going down in lower weights when you are boating with a freshwater cooled 160-170 degree constant cooling temperature engine like the 496 -Merc..
Stay with the recommendations from the 496 marine engine manufacturers and stay with either 25-40w or 20-50w synthetics or blended synthetics.

Just my professional opinion.

Best Regards,
Ray @ Raylar