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What engine oil grade

G

gkm24

Regular Contributor
"I have just drained the oil f

"I have just drained the oil from my 350 magnum (approx 1991) and am changing filters etc. What is the best oil to use ie synthetic, semi synthetic etc and also the grade. Thanks."
 
"This scab hasn't been pic

"This scab hasn't been picked in a while!

I use SAE 40... engine oil. If you use the boat in primarily the warmer months or are in a fairly constant temperature zone (like Florida) Multigrade oil (10W- or 20W-whatever) doesn't do much for you.

Synthetic oil isn't any slipperier than petroleum based oil, but sure does cost more. Folks will argue that synthetic oil will make the engine last forever, where other oil will let you down.
All other things constant, (temperature, type of use, etc.) the most damaging effect on lubrication comes from contaminants in the oil. Synthetic oil is not exempt. Engine wear products, water, and combustion products build up. Under normal conditions, oil doesn't wear out. But, the oil filter only gets rid of the big chunks. For the small engines we are discussing here, there isn't any type of purification system, only replacement.
Regardless the type of oil, if you don't routinely change the oil and get rid of those contaminants, the life of the engine will suffer.
Perosnaly, I don't see the point in spending 3-4 times the money for synthetic oil."
 
"In my cars, i use mobil1 5-30

"In my cars, i use mobil1 5-30 and i see both an improvement in temperature and fuel economy(esp when towing the boat) Where i have always read that syn oils excel is in high temp situations, and my experience seems to corroborate that. The boat is a different story altogether. I use what my manual says to use, merc 25-40 and ALWAYS ALWAYS ALWAYS merc marine oil filters. Because the oil filters boats use filter less than cars, i've been told time and again it's more important that you are changing at regular intervals than if you use syn or dino oil. Were i you i'd find out what the engine shipped with and put that in and not give it another thought.

--chris"
 
""Because the oil filters

""Because the oil filters boats use filter less than cars"

Chris: Interesting statement; can you provide a source or study to corrorate it?
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"I hear straight weight oil is

"I hear straight weight oil is the way to go on boats. Two ways to wear out oil: termal breakdown and contamination. The latter as troy says is what to worry about.

Auto makers suggest multi weight oils as low as 5 for fuel economy reasons, btw. Takes a lot of power to pump cold thick oil.

I hear the "use Mercuiser filter" call to action from Mercruiser, but thats about it. Not sure i believe it makes a great deal of difference if you are changing your oil regularly."
 
"I thoroughly investigated thi

"I thoroughly investigated this issue last year when I installed a new crate engine. After exhaustive research I determined that 15-40 heavy duty oil is the best choice, either Rotella T or Chevron. Both oils are commonly used in diesel engines. Low weight oils, such as 5-30 are just too thin for marine engines."
 
Another thing to think about i

Another thing to think about is how many hours does your engine have. The older and more useage an engine has the more prone to seals and gaskets leaking if you switch to Synthetic at this time.

I just bought the Sierra eqivilant to Quicksilver brand motor oil and filter. We'll see.
 
"Guy--
I've been told

"Guy--
I've been told from multiple sources that marine oil filters do not filter down to as small a particle size for flow concerns. Because marine engines turns on average much faster than car engines, the filter elements are coarser than the automotive grade filters. I have even read that putting an automotive filter on a marine engine can lead to oil starvation issues. I think i may have even seen cross sections of the things. Looking inside the filter i put on my boat last year i did notice it looked different than the automotive filters(I think it may not have had a silicone anti drain back valve, cant recall now). Am I off base on that thinking? If so let me know, i certainly don't want to spread bad info, i hate that.

--chris"
 
Chris:

You have made some g

Chris:

You have made some good points. I guess I should do what Bondo does and get WIX filters from NAPA. I was using Shell Rotella T 15W40 but switched this year to Mobil One 15W50 to see how it affects my engine.
 
This quote comes from the abov

This quote comes from the above site:

"Do you guys know that Quicksilver uses 50 micron filter paper in their oil filters which means that no particle larger than 50 microns will pas through the filter. Whereas your standard car filter uses 100 micron paper. Which one would you use. I'll spend the extra 3 or 4 bucks for a marine filter."

"AC Delco Filters: (from their Web site):

AC Delco "Duraguard Silver" Filter Traps 15 microns particules;

Ac Delco "Ultra Gold" 8 -10 Microns."

Did I pull the scab off?
 
"My nickle's worth:
The 5

"My nickle's worth:
The 50 and 100 micron sizes referenced above have to be dead wrong.

One micron is one millionth of a meter. A 100 micron particle is 0.1 mm size, or about the size of fine grain salt. This means that a 100 micron absolute filter will pass all particles 99 microns size and smaller. Your oil filter better be doing one h*ll of a lot better job of filtering than that, or it might as well not be there at all!

The usual numbers referenced for lube oil filters are 5 and 10 micron particle sizes, and I believe that this is where marine oil filters are at. I remember reading that Merc's filters are rated at 5 micron.

Rod"
 
"All--
I have looked and l

"All--
I have looked and looked but i cannot find the original source on which i base my statement that marine oil filters don't filter down as small as automotive for flow reasons. I have found several posts on other forums(by schmucks like me) saying it but i *swear* i saw it in print from what i would call a primary source(like a manufacturer), but seeing as how i can't find it, I am going to back off that statement(but i'll only put merc filters on my boat ;) )

Now on another note, my 2+ hour research last night did yield this cool link i thought i'd share

http://people.msoe.edu/~yoderw/oilfilterstudy/oilfilterstudy.html

i'm rather glad that i use pur one filters on my cars


--chris

ps: officially sorry for any scarring incurred as a result of this thread
"
 
"Very interesting, indeed. I&#

"Very interesting, indeed. I've always been a hardend Fram oil filter user; not for the boat, but all my cars for as long as I can remember. After reading the article, I'm seriously reconsidering, especially since there's not much of a difference in price. As far as the boat goes, I'll stick with the Quicksilver filter."
 
"i look at it this way; even i

"i look at it this way; even if the merc filter is 20 bucks, so what? The motor is like 5000, so i figure the 20 bucks is worth it. I don't recall the merc filter being any more expensive than the pure-one filters i buy for the car and truck anyway, they all seem to be in 10 dollar range +/-. The info on that site i linked seems to be a bit old, but i bet alot of the info (if its not updated) is prob still relevant anyway. I knew about the problems with fram filters going back a while(i went to buy one at an auto parts store and the checkout guy told me not to, and went on to explain why) so his results did not surprise me on that end.

--chris"
 
"Very interesting. I have, for

"Very interesting. I have, for the time being, gone with a semi synthetic 10-40 GM oil and a Sierra Oil Filter. The boat is a 91 Celebrity with a 350 magnum and 190 hours on the clock. i only use the boat about 20-30 hours a year at very most so its not as if the oil stays in there very long and I don't thrash around at full throttle. I may convert to Merc oil filters though. On another note, as gas prices here are now $9.60 a gallon( yes thats right) I am going to convert to LPG fuel. Anyone know of a good system I could get shipped over??"
 
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