A simple oil question

[Bryan Tuvell 33ZX]

Well our season as ended, I staerted my winetrization routine today, as my day watche 18qts of my high dollar 25w 40 drip out of my oil pan tubes, a guy started chatting me up, says he uses 15W 40 non Merc.

What is he missing, or what I am I gaining.

Just curious and expanding my education.

Still hope to repower in the near future, time will tell as my life constantly changes... thanks to our newest Commander In Chief. I can not WAIT for April 2010 to retire.

Bryan

[Dr. David Fleming]

MOtor oil is one of the most discussed and argued subjects except maybe gasoline. The subject never ends and neither do the opinons. Sometimes personalities are revealed in the statements. "Cheap b...... never put a nickel in the engine he didn't have to." "Nothing but the best for baby!" the difference between the oils you mentioned is viscosity or thickness and the quality and expense of paying for 15quarts at $6.00 or $3.00. $95.00 for an oil change vs. $45.00. If you had to put all the precision machining into the engine that the manufacturer did you would go with the $95.00.

Racing motors use thicker oil usually because their internal tolerences are set looser because they make more power that way and because the forged steel and aluminum parts they are made of expand and contract more. If you look at the Merc service literature the 502MAG MPI and 454MAG MPI use looser tolerences - I think the 502 has something like .006 piston to cylinder wall clearance when cold. Modern cars (Merc 7.4MPI is a pickup truck motor) are something like .0015 which is 1/4 the thickness of a sheet of typing paper. The big Merc is 1 and 1/2 sheet of paper clearance. SAme with the crankshaft and rods - looser and they need thicker oil - some folks like to run SAE 40W racing oil.

You can't go wrong using what the manufacturer recomends.

Dr. d

[BlownCrewCab]

You don't need high Dollar, And you don't need Multi Viscosity. Straight 40w is all you need. Being "Cold Water" cooled your engine temp stays pretty cool and doesn't vary too much. (unless you boat during the winter) And you don't do cold starts like you do with your car (may be freezing out) your temp range in your boat is usually within 40* (your not going boating if it's below 60*, Right??) whereas your car will be used in a spread of 100* if it's zero out- Or if it's 100* out you use your car--> And Thats when you need Multi Viscosity------> In Your boat you do Not!!!

[BUIZILLA]

I think the 502 has something like .006 piston to cylinder wall clearance when cold. Modern cars (Merc 7.4MPI is a pickup truck motor) are something like .0015 which is 1/4 the thickness of a sheet of typing paper. I think your going to find that piston MATERIAL has a lot to do with that...

[MOP]

And I like multi grade syn oil!!! And this will go on and on! IMO any good quality oil is just that! Choices are infinite the opinions are also!

[Bryan Tuvell 33ZX]

I always get the best answers here, thanks.
So the first number is thickness on a cold start and the second number is when it is hot???
Bryan

[Dr. David Fleming]

I just did this on another thread. The SAE (Society of Automotive Engineers) number of the oil is its thickness. 10 is thinner than 40. The W rating on a multi viscosity oil is its winter rating. 10w-30 is a multi viscosity oil. What this means is that it is rated 10 for winter driving and 30 for summer. How does it do that? Well there are chemicals added that make it act like a 10 in cold and a 30 in hot. People often confuse the W with "weight" of oil which is a name given to the SAE rating in slang. "What weight oil are you using?" "I am using 30 weight or SAE 30.

The API rating which you see on the can also is a relative term indicating the amount of additives and detergents in the oil and what year specification they meet. I think the API started in the 1960's when they used rating SA for gasoline and CA for diesel engines - I don't know what API they are up to now as I usually don't pay attention but I think it is SG and CG. These high API (American Petrolium Institute) indicators are to tell you what quality oil you are buying in order to keep your car warrenty in effect - you must use a specific quality of oil.

Oils are also rated as mineral - from the earth, and synthetic - liquid plastic material with teflon and other chemicals. The synthetic was developed in the 1970's as the famous "MOBIL ONE" and there are Valvoline synthetics etc. Basically they last a long time and don't disintigrate into their primitive elements like mineral oil.

Oil fills up with carbon, water, acid, dirt and metal particals when it is used in the engine. It is destroyed by heat and age and after while it isn't very good at doing its job of cleaning and lubricating the engine. Engines that run full bore like marine engines really beat the crap out of oil. Your car goes full throttle once in a great while. Marine engines go full throttle most of the time if you own a Donzi. So the oil must be changed often. The filter is just as important.

The oil is so bad coming out of an engine that it is known to be a cancer causing agent. Used motor oil is filled with heavy metal patricles and it is not good to get it on your skin. Most cities are eliminating automotive junk yards because of the danger of leaking crankcase oil getting into the ground and destroying the water supply. The green folks are really ballistic about this. There is a federal law about spilling gasoline and oil in the lakes and waters of the USA and if you see it and report it, your marina will get in trouble. they are always spilling gas and hoping the Coast Guard looks the other way. The same with your bilge water - you are not supposed to pump oily bilge water into the lake - yah right!

Dr. d

[oledawg]

Said before, and saying it again, if multi viscosity synthetic is good enough for my Harley, it is good enough for my Donzi. Compared to other costs of owning a Donzi ( or any boat ), using the best oil is cheap. :cool!:

[The Hedgehog]

I use Castrol 20W-50 in my 850. It is what Eddie Young told me to do so I do it. He builds BIG power engines that last and has studied the subject so I listen to him.

I went with straight 40 in the Procharged 502 mag. In that case my engine was getting tired and the tolerances were getting bigger. Like Dr D said, this worked in this situation. It brought up my idle oil pressure on those hot days.

Synthetic is good if you have an engine that can handle long intervals between changes. I favor more oil changes over expensive oil.

I have never used Merc oil (other than drive oil)

[oledawg]

Now that is an interesting point, exactly what is the best interval for changing oil? Hours? Months? Seasons? I think that you have to assume that most Donzi owners run their boats fairly hard, I know that mine rarely is below 3,000 - 4,000 rpm. :cool!:

[Bryan Tuvell 33ZX]

I would guess at about 20 hours. That in reality is allot of boating. I usually change at the start of the season, have it done in the mid season and do it again at winterization.

I appreciate all the feedback, I was just curious.
Thanks for all the good data.

Bryan

[MOP]

Where is Chachi this could be another interesting one:popcorn:

[Air 22]

We use BRAD PENN® PENN-GRADE 1® Partial Synthetic SAE 20W-50 High Performance Oil in our HP500EFI.

Bill @ ATECO engines runs Brad Penn Racing Oil in all their engines and put me onto this stuff :wink: ( btw it isnt anymore expensive $3ish a qt)...its one of very few oils the still contains Zinc and Phosphorus. These two properties are not found in automotive oils due to emissions requirements and have been removed to meet EPA automotive standards...

" The Brad Penn® Penn Grade 1® High Performance Oils contain the higher level of anti-wear (ZDDP – zinc dialkyldithiophosphate) and enhanced film strength so critical to proper high performance engine protection. The Penn-Grade 1® oils “typical” 1,500 ppm Zinc (Zn) and 1340-1400 ppm Phosphorus (P) content provide the needed anti-wear protection to critical engine parts, such as piston/cylinder walls, roller cams under heavy valve spring pressure and especially those that employ a solid “flat tappet” type system. As important as the chemistry is to the Penn-Grade 1® oils, it is by no means the whole story. The unique base oil cut used to refine the Penn-Grade 1® High Performance Oils maintain a tremendous affinity to metal surfaces. This naturally occurring “metal wetting” characteristic enables the oil to stay put on your highly stressed engines and makes the Penn-Grade 1® High Performance Oil resist slinging for an extended period of time. Also, rest assured in knowing that the Penn-Grade 1® High Performance Oils are 100% Made in the USA."

http://www.bradpennracing.com/Products/racingoils.html


http://www.amref.com/CMSFiles/File/pdf/Products/Engine-Oils/Penn-Grade-1-High-Performance-Oils/7126_50_44_58_19_BP_PG1_Multigrade_HP_Oils_PB.pdf


In the end what really matters is changing the oil ...we change it every 20hrs...Clean oil is a must.:wink:

[Carl C]

"A simple oil question.......:nilly:"

[The Hedgehog]

Now that is an interesting point, exactly what is the best interval for changing oil? Hours? Months? Seasons? I think that you have to assume that most Donzi owners run their boats fairly hard, I know that mine rarely is below 3,000 - 4,000 rpm. :cool!:

It depends on how it was set up and how you run it. 20 hours like Air said is probably a good rule of thumb. My 383 in the 18 looks good even at 25 hours or so and my 850 needs it at 10 hours.

[fasttrucker]

I try to change my oil once halfway thru my boating season and then change at the end of the season.That works good for me and my wallet.:wink:

[Bryan Tuvell 33ZX]

Carl..... great point.....
But I am getting smarter. I really did start with a simple question.

Thanks to all for the time the spent posting.

Bryan

[CHACHI]

I am here, Brian you have mail.

Dr D.a 10w oil is MUCH thicker than a 30 because they are rated at two different temps. If you don't belive me, pour some 10w 30 in a paper cup and stick it in your freezer overnight and in the morning see how fast it pours out. THEN take the same oil and pour it in a frying pan and heat it to say 210 degrees, and then pour it out. I will guarentee it is thinner than the same oil that came from the freezer.



Oh, the Germans invented synthetic oil during WWII because they had no oil reserves.

Ken

[Shanghied Again]

Hi Brian. On the 496/HOs the recomended oil is 15-40. I use regular Merc oil not synthetic. you can use synthetic but I feel with the boating season short and the 496 being a stock engine there is really no need. I do change my oil after 50 hours of use. I have 340 hours on my 33 and she still has 60 pressure on oil, I just did a leak down and compression test and she is still good as new. I also added a Quick change pump to my engines so I can hook up to a pump and change the oil in 5 minutes per motor. I just feel going for expensive oils have no gain on a 496 and it is just a waste of money.