PDA

View Full Version : 10W40 vs. straight 30 weight



Air 22
06-26-2002, 09:40 AM
Help???My owners manual for my 22 Classic w/ a 1995 7.4 385hp Merc says run Quicksilver Marine Engine oil as a 1st option then as a 2nd choice either 10w40 or less of an option 10w50 weight oil. Quicksilver 1st is a selling point for Merc but my marina says they only run a straight 30weight in all boat engines. They claim 10w40 is to light for a high RPM engine like a boat 2000-5000 RPM. I told them my owners manual says 10w40 and they looked supprised? I'm runnig MOBILE 10w40 nonsynthetic as this what was in the engine when I bought the boat. Should I switch to a fully synthetic oil or could this cause seal problems..leaks etc?

ThrillSeeker
06-26-2002, 09:46 AM
How many hours are on your boat? It realy shouldnt matter. I would switch to the full syn. or maybe go halves. They make a 50/50 mix. It probably would be better if you went w/ the 10w30, but dont worry about it they are almost the same.

CnV & Family
06-26-2002, 10:01 AM
I stand to be corrected, but I believe the overall consensus is to run a straight 30 synthetic in performance applications. I personally still use the 10W30 although we've only got a 4.3L V6...

Do a search on synthetic or oil preferences. There were some very extensive and detailed threads on that very subject not too long ago.

-C

Air 22
06-26-2002, 10:04 AM
The engine has 150hrs on it. No problems yet with the oil. I changed from nonsynthetic to a fully synthetic oil in a re-built 350 engine a few years back and the damn thing leaked (main eng seal) I changed back and the leak stopped. I don't want to run into the same problem w/ this 454. I like the working protection of fully synthetic oil but is it going to leak?

ThrillSeeker
06-26-2002, 10:12 AM
CB&V was right u shoud run synthetic in performance apps. But if you are woried go w/ the 50/50 blend would be what you should try. The motor is just barely broke in, Ithink
You would be fine swithching to a full synthetic.

RickSE
06-26-2002, 10:18 AM
My manual states to run straight 40W, so I run Valvoline 40W.

Air 22
06-26-2002, 10:19 AM
Ok..I'll try a fully synthetic blend at first then change to all synthetic next oil change. I'll stay with Mobile 1 10w40 unless a staight weight is better?

Air 22
06-26-2002, 10:21 AM
RickS..What type of ENG and year are you running? a 454 or larger?

Forrest
06-26-2002, 10:25 AM
According to most oil experts, any brand of petroleum 10W40 isn't even fit for your $99 lawnmower. If you need a 10W based viscosity petroleum motor oil, you should use should used 10W30. Apparently, 10W40 petroleum-based motor oil has an abundance of viscosity improvers that ultimately cause degradation of the product. Big Grizzly probably has a few words on this subject and maybe he expand on it somewhat. In any event, you would be good to use the 25W40 that Merc recommends, or straight (SAE) 30 or for that matter, or if it's really hot where you are, SAE 40 would be a good choice. Of course, all the above goes out the window with fully-synthetic motor oils. Though I'm sure that, Red Line, AMSoil, Royal Purple, and the like are top choices in synthetic motor oils, I run Mobil One 15W50 in my marine engine since you can buy it almost anywhere for a reasonable price. Well, reasonable as far as synthetics go.

Air 22
06-26-2002, 10:35 AM
Mobile 1 fully synthetic 15w50 sounds like a good choice. I'm running in ave temps northeast and mid-atlantic although its been hot lately 90's but water temps in the 60-70's. Thanks for all your help.

Rootsy
06-26-2002, 11:02 AM
there were a few extended discussions on this subject earlier this year and in the past... you might try searching the archives.

RickR
06-26-2002, 01:58 PM
I use Castrol Heave Duty straight 40 and Fram filters in my 1995 454 Mag .

Last winter I had to tear engine the engine down because the aftermarket cam I installed failed.

Oil is changed twice a year.

After 550 hrs (except for cam failure damage)bearings, cylinder walls, pistons, timing chain and OE cam were in "like new" condition. #3 and #5 Rings had a little wear because of a leaky riser gasket and valve seats were beat up.

RickSE
06-26-2002, 02:42 PM
Dwight it's a 1996 350. I typically run in 100+ deg. weather. Valvoline is the only straight 40W oil I can get here in town.

Air 22
06-26-2002, 02:54 PM
OK... Anyone have a problem with a full syntheic MOBILE ONE 15w50 weight oil? I run 30-50 hours a season.

blackhawk
06-26-2002, 04:13 PM
The biggest problem with engine oils is it doesn't get changed often enough. Sure, synthetics are a better lubricant but petroleum based oils were fine too. Most of us take very good care of our boats and change the oil enough so that we don't have to worry about it.

MOP
06-26-2002, 06:30 PM
I want in on this!!! If any of you are foolish enough to fully believe the OEM boys you have need to look at thing alot different. Any decent SAE engineer will tell you to run straight weight oil, in your car multi grades are fine. When you get you car or rig up to speed you ease up on the peddle, in you boat you just keep the throttle set which keeps a heavy load on the crank shaft bearings. Synthetics are great, most suppliers can get you straight weight. The Mobil site shows all the grades you just have to find a dealer that stocks or will order for you. Now back to the OEM trust issue. I had the opportunity to work on the owner of Sendure's (One of the largest makers of heat exchangers) boat he happened to break it on my turf. I being my usual crusty self crabbed about the fact that if I had (TEN) over heats a month (NINE) were fresh water cooled. I could not believe what I heard from his lips! He had an agreement with the OEM boys to a 15% margin on tubes in the coolers, he said 8-10 tubes plugged and you are on the edge of over heat. Then he laughed and said the only thing that is not warrenteed is over heat that was OEM's anuity. Stock OEM colling is marginal! Having worked on this stuff for over 40 years I DO NOT TRUST ANY OEM BS ABOUT OIL!

MOP
06-26-2002, 07:33 PM
Hi the roller issue is interesting, would like to hear from a cam maker as to thier thoughts. I have always gotten about 20 hours or 15,000 miles on my boats or cars/trucks before going over to Synthetic. I did alot of questioning of a Mobil tech at a show years back and his tilt was unless the engine is clearenced and polished when built let it break in and clearence its self before swithing because it is so slippery. and don't put in in well used motors as they will leak like crazy. I and I am sure many have seen a good jump in gas mileage in my vehicles. Back to the roller issue, Mobil comes in the hot Vetts from the factory. Are they roller motors? I am running a 50/50 mix in my 16, its not a roller setup. I would be intersted in some input as I may be caming up with rollers!

Paul Storti
06-27-2002, 04:18 AM
I use castrol 40 weight change it every 50 hrs.

Shanghied Again
06-27-2002, 04:55 AM
I have used Vavoline Racing straight 40 in all my Marine motors.

Gary S.
06-27-2002, 07:29 AM
Straight 40 weight changed every 50 hours is all that goes in my boat's because it works. Our last two charter boats were traded in when the fishemen had them so beat they weren't worth washing anymore both had over 3500 hours, and that was nothing special. I don't know many Captains who do anything diffrently, and I can't recall any who haven't wore out the boat before the engine, that's enough proof for me. As far as the 15W-40's Rotella, Delo, ect. they are great DIESEL oil's, EPA's new emission standards really strained the oil's thats where most of the soot goes now,, in the oil, and the lubricant manufactures responded with fantastic oil's. Will I put them in my boat ? NO. The diesel spends most of it's life in it's optimal range, our boats do not. Same thing with cars and 10W-30, diffrent RPM's and load. I don't think you can compair on-highway and marine engine preformance, they are two diffrent worlds. Just my 2 cent's from life's lesson's, it's Valvoline 40 weight for me.

Air 22
06-27-2002, 10:18 AM
Sounds like the general consensus is to run a straight(MOBILE ONE) 40 weight oil in my 1995 454MERC w/150hrs on it. Running 2000-5250RPM is not what a car typically runs at... Unless your in DAYTONA in FEBRUARY.
Thanks for all the help. Didn't expect such informative informational responses.

Rootsy
06-27-2002, 10:26 AM
do synthetics work well in automobiles? sure... in boats? i donno but i would imagine so... me, i stick to valvoline racing 30, changed every 25 - 30 hours... it hasn't even begun to discolor when i replace it. my motor is 5 years old and when i popped the heads this spring the hone marks were still very prominent in the cylinders and the valveguides were unworn and there was no lip at the top of the cylinders. years back i had a customer with a 38 cig top gun... running hawk marine power... new motors didn't have 10 hours on em and they wiped the camshafts... he was running synthetics with a roller setup... replaced the camshafts and it did it again... 3rd time comp said do not run synthetics for the first 25 hours... replaced the camshafts followed their advice and never had another issue with the motor... go figure... was the issue with the valvetrain or the oil? i'm no expert but i don't want to take a chance in the boat since i run a roller setup at higher rpms than an auto motor runs... but many do run synthetic as well as a lot of new cars and the new cars are mostly all roller camshaft setups... so it is probably personal preference...

BigGrizzly
06-27-2002, 03:41 PM
I spent 6 month evaluating oils for my company. Never use 10w40. It is the worst oil any company produces regardless of whom. In 1984 GM sent a bulletin/memo to its dealers stating it would void all warranties if 10w40 was used. In all test over 50 different brands of petro bast and 25 synthets oils every one out proformed the 1040 even 5w105 petro based. I have gone through this 7 times on the net so I'm writing less about it. My suggestions are -not in order 30w 10w30, 40w and any name brand plus good synt oils such as Amsoil, Red-line oils.

Randy