need help i have a 312 with twin 6.2 s. boat gets stored in heated garage for winter. well i uncovered it to get it ready for weekend and to change oil . i notice that left motor oil was milky.has anybody ever have this problem.no loss of power last year or over heating. i did notice hearing a noise coming from exhaust at a certain speed. somebody said that it may be possible to get water in oil if manifold is bad. any idea please help.

What year? how many hours,salt or fresh,new style risers with dry gaskets?.I got four years and about 250 hrs out of my risers.I run in salt but always flushed.
First thing get that oil out if you if you have not already.You can use any oil as you should change it a couple of times to flush it.Then pull both risers it easy just unbolt the ECM from one side and the throttle linkage from the other.Then remove the four bolts on the top of the risers.When you pull them off look inside if you see rust stains they are bad.Then you have a choice just change risers or do what I did and redo entire system with IMCO its much lighter and made a world of difference coming on plane.If you do decide to just replace the risers I have one in exellent shape with about 10 hours on it so you can save a little money.

And I know its Memorial day weekend but don't run the boat.If it is the riser you will be spraying the exhaust valve with cold water....they don't like that.

havent run boat yet. its a 2001 312 fastech motors have about 46 hrs on it .should i run new oil first or take riser off. thanhs dave.

2001 with 46 hrs?.Or were the motors rebuilt recently,if so who did them that changes things a little if the motors have been apart recently.If the were how many hours on the exhaust even if they only have 46 hrs 11 years on risers is a long time.

I would drop the oil out it will give you a better idea how much water is in there.Put new oil in run for like 30 seconds to circulate.Then pull the risers to check them.

change exhaust intakes and gasket set. risers were ok. sand blasted and powder coated them. change oil about 5 times just to make sure water was all out. scared the s--t out of me. thanks for info.hope to go to a bay buy weekend and give it a run. thanks again dave.