can I put diesel oil in my engine ?

Caveman Charlie

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Re: can I put diesel oil in my engine ?

They make a straight 30W oil for older diesel engines. We used to use it in our tractors on the farm years ago. But, everything made after the early 80's calls for 15w40.
 

Caveman Charlie

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Oct 31, 2007
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Re: can I put diesel oil in my engine ?

I bought my boat last fall and only had the chance to get it in the water a few times. I see in the book now that my 74 Mercruiser 140 calls for 30w MS or SD oil. I'll probley use the old 30w diesel oil we still have left on the farm.

Now if only I can figure out how to drain the old oil.
 

starsnstripers

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Re: can I put diesel oil in my engine ?

Would changing to a synthetic oil in an old engine be better on the rockers?
 

johnbo

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Mar 19, 2006
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Re: can I put diesel oil in my engine ?

I've been using Delo 400 30 wt in '96 4.3L. At least in Oregon, its available at Costco, BiMart and other shops. Its a straight 30 wt, diesel rated oil. I use the 15-40 formulation in my Ford PowerStroke.

Hope that this helps,

johnbo
 
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flabum

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Feb 17, 2007
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Re: can I put diesel oil in my engine ?

Funny thing..... Rotella is not FCW rated
 

Scaaty

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Re: can I put diesel oil in my engine ?

Funny thing..... Rotella is not FCW rated

Either is any of the other straight or multi-weight oils used in car engines, which are all the same as most I/O's.
The FCW oils are specific to the new 4 stroke outboard motors
 

bandit86

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Re: can I put diesel oil in my engine ?

most aircooled engines prefer 30W even though you can use 10W30. at extremely high temp and loads, like a boat at wot or a lawnmower in summer cutting 3 weeks worth of grass, temperature breaks an oil down.

the only downside to diesel oils is the sulphur. I even run rotella 15w40 in my riding mover
 

Don S

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Re: can I put diesel oil in my engine ?

Get a grip guys, no one ever lost an engine because of using the wrong type of oil, and every type known to man has been used in a boat.
Use whatever puts a smile on your face and change it (and the filter) every 100 hour or yearly which ever comes first and you will be fine.
Engines die from water, lack of maintenance, and tinkering when you don't know what or why you are doing it. Most problems with boats could be avoided by having an OEM service manual, and following the maintenace schedules and procedures.
 

JustJason

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Re: can I put diesel oil in my engine ?

neat pic.. where'd you find it?
 

Don S

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Re: can I put diesel oil in my engine ?

No one wants to go boating at -35?C (that is -31?F). Besides that, the water is frozen, even salt water. So what is the point?
Is there some wierd strange reason that good common sense is not used in these oil threads? You use whatever you want in every other vehicle you have, but you have to make a big deal out of it with a boat.
 

Lou C

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Re: can I put diesel oil in my engine ?

I recall seeing similar pix advertizing various brands of synthetic oil. And most people may be over-thinking this, just use what the manufacturer recommended, if you have a Merc use the Merc stuff, who cares if it costs more you only change once a year. If Volvo, yeah the syn straight 30 is hard to find and expensive, but still you do it once a season, just use what they say, I usually don't second guess engineers. As for me, I use what OMC recommended, straight 30, and even when I have started it as cold as 45* it still starts fine. I'm not boating when it's below 65 anyway! I do think for most people boating, using a straight weight with no VI improvers does help things since deposits from them can cause trouble and a multi vis oil still tends to shear down more than a straight weight, which is probably why, Volvo recommends straight 30 and the Merc oil is really not a true multi vis but a combination of 2 straight weights.

that pic is why I like a 2 stroke snow blower with electric start, no probs starting at the coldest temps (we only get to zero here once in a while), except for the nice big blue smoke cloud at start up!
 

Uraijit

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Re: can I put diesel oil in my engine ?

I recall seeing similar pix advertizing various brands of synthetic oil. And most people may be over-thinking this, just use what the manufacturer recommended, if you have a Merc use the Merc stuff, who cares if it costs more you only change once a year. If Volvo, yeah the syn straight 30 is hard to find and expensive, but still you do it once a season, just use what they say, I usually don't second guess engineers. As for me, I use what OMC recommended, straight 30, and even when I have started it as cold as 45* it still starts fine. I'm not boating when it's below 65 anyway! I do think for most people boating, using a straight weight with no VI improvers does help things since deposits from them can cause trouble and a multi vis oil still tends to shear down more than a straight weight, which is probably why, Volvo recommends straight 30 and the Merc oil is really not a true multi vis but a combination of 2 straight weights.

that pic is why I like a 2 stroke snow blower with electric start, no probs starting at the coldest temps (we only get to zero here once in a while), except for the nice big blue smoke cloud at start up!

Why use the Merc stuff? My pay more for the exact same oil? I agree, it's generally best to use whatever viscosity the manufacturer recommends, but manufacturer's "special" brands generally tend to be snake oil, as it were.

As engines age, a heavier viscosity oil helps to keep your bearings from slopping and accelerating wear. Manufacturers don't mention this, because once it's out of warranty, they'd rather have you come back and buy a newer boat/engine sooner. Why would they tell you how to get the maximum life out of an older engine?

FWIW, combining straight oil weights gives you a split difference in weights. In motorcycles if you want a 7.5 weight fork oil, you get a bottle of 10W and 5W and mix 'em. Voila, 7.5W fork oil! ;)
 
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