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Discussion Starter · #1 ·
Was told today by my local marine shop that burning a quart per 100 gal of fuel burned in my Fastech 271 with 502 is excessive?

The manual says oil consumption is normal but is vague on what constitutes normal.

Anyone else burning the same? No blue smoke on startup or leaks in the bilge and boat is not ran hard at all, 95% 3000rpm cruise.

Was thinking of moving to Mobil 1 synthetic from current Mercruiser 25W40 but Mobil does not offer a direct 25W40 that I can find. Any ideas on that as well?

Is genuine Mercruiser Oil just a rebadge of a Valvoline or Quaker state, etc?

Just wondering, thanks for any help!
 

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It sounds normal. I burn about the same amount of oil on a 502 especially in July, and August when its very hot and humid.

If you have been using regular oil (Mercruiser 25-40W) in your boat since you have owned it, I would not recommend switching to synthetic. I have seen gasket problems happens when switching from regular oil to synthetic.

Just my 02 cents...... :)
 

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Discussion Starter · #4 · (Edited)
thanks guys, the guy said the boat should burn the same as a car..........

that should have been my first clue he was a blowboater.

car with same displacement gets 25mpg on hwy, boat gets 2.5mpg at cruise, little thing called drag, ha.

with 10 times the load on the motor I would think a boat would burn a tad more oil than a car, ugh.
 

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boy thats a sharp 271, I ran a poker run lat week, running around 4200-4500 prm with the occasion open er up and my consumption was about the same, I too have been told this is normal and don't worry bye a pretty good engine guy
 

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Mine 502 burns about a quart or so every 10 hours, which I believe the merc manual claims is normal. My 454 mag burned about the same and that one only had 100 hours when I got it.
 

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Big Blocks Burn Oil No question about it... Maybe 1 qt to 100 gallons is alittle more then avg But I dont think you have anything to worry about... Thats only what $5 in oil per $500 in fuel...

I say Run it!! :cool:
 

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NORMAL.....502's are known to last forever and that little bit of oil that coats the cylinder walls is what helps it last so long.
 

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502's like oil,,,,nature of the beast.
 

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I check mine every time we go out and it does burn about the same amount so like they said before.....run it!! But always check first!
 

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All 502's have a low tension oil ring.

Price you pay for performance !

BTW: Not only will you burn a little more oil than you are used to with other engines but your oil will also get diluted quicker with fuel.

Check your oil level before each trip (you should do this on all motors anyway !) and also take a quick wiff. If it's turning black and it smells like fuel (oil and fuel smell different) then get your oil changed.....which you do every fall anyway right ?
 

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Maybe that is why they last so long, they always have fresh oil in them!! :laugher:
 

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I jus change mine when it doesnt look purple anymore. about 10-15 hours. with the big ol oil cooler new lines and remote filter mount holds like 9 quarts to fill it.
 

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Sounds normal for a 502. I switched to synthetic at 120 hours with no problems. But I will not use Mobil 1. I have been using Rotella T because a bunch of people with V-10 Fords say they burn oil while using it. I have had no problems with Rotella T. My 2 cents.
 

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Ikes brother said:
Every fall!!!? How bout every 10 -15 hours. Maintenance freak....but it gives me peice of mind ;)
I'm sorry. I forget most have a much longer boating season than us. :laugher: :laugher:

We have only 3 months on average to boat. :dead:

10-15hrs is excessive. But that's better than blowing it off !!! :D
 
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