Should my engines be using oil?

Moneyplays21

I have a 2014 310EC with twin Merc 350 inboards.  I regularly check the oil and they are using a quart ever 50 hours.  Is this typical/correct????  I run a lot at 7.5mph and a lot at 28mph.  I try and run them at WOT for a couple minutes every time I go out as well.

skennelly

Moneyplays21 - Both engines are using the same amount of oil?  Have you checked the plugs...how do they look?

I would say some oil consumption is going to happen...what's normal is hard to say.  1 qt in 50 hours doesn't seem too bad.

Moneyplays21

Yes, both using the same amount.

frenchship

 Maybe I am mistaken but it seems to be excessive, on a 2 years old motors. Maybe Al would comment on that.

Handymans342

What oil are you using?

Moneyplays21

25W 40 Marine Synthetic blend

Handymans342

That does not seem like the right weight

randy56

I think that's what the manual calls for. Seems an excess amount use in 50 hours. Mine does not consume near that much. 

MarkB

1 quart every 50 hours for both or each engine?  For both, that isn't bad.  These engines do burn some oil, especially when you are loading them.  You'll see consumption go up if you have a heavy load, or are +80% of WOT. 

A quart every 50 hours per engine would be a bit higher than normal ... but again if you are regularly hauling 10 people and stuff ... you can get higher oil consumption.

Michael T

Moneyplays21, I have owned seven 350 Mags, including a 2013 Rinker EC 310 with twin 350 mags. They all burned very little oil. In fact burned would be the wrong term altogether. The 2013 350 Mags I had never used enough oil between oil changes to top them up. They simply didn't consume oil. These engines are very energy efficient and sturdily built. As mentioned, unless you are loading your boat to the maximum and those engines are spending a lot of time in the upper RPM band something is wrong, according to my experience with them. Did you purchase the boat new? Did you break it in according to Mercruiser specifications? IMO if you are using the synthetic blend recommended by Mercruiser you should not be consuming so much oil. If you are using another manufacturer's oil I can't comment as my 2013 350s only used Mercruiser Synthetic.

Handymans342

Oh no, hes back

rasbury

Glad to see you back @Michael T !

BellevilleMXZ

Michael T said:

Welcome back.....hows the holidays :-)

Black_Diamond

1qt every 50 hours seems like a lot to me.  My 350 MAG MPI's use virtually no oil, or certainly not noticeable on the dipstick.

Robs_232

My 2004 350 Mag doesn't move on dipstick all year, but I have never put 50 hrs. on in a year either. I always have the oil and filter changed as part of winterizing. I'm with Al on how long are you going between oil and filter changes.

wm61356

I have 350 MPI Mag's in my '09 320 with a little over 300 hours on them. I run the Mercruiser recommended oil and change the oil and filter at 50 hours or once a season, whichever comes first.  Each motor will consume a few ounces of oil in 40 to 50 hours use, particularly if I've taken several long trips (3-4 hours at cruise speed). Never had to add anywhere near a half quart let alone a whole quart though, and never had the oil level drop anywhere near the "ADD" mark on the sticks. There are no leaks and compression tested fine. I just figured that, given the load those motors are under,  being down a couple ounces of oil isn't anything to be worried about.